„,.»'»".'*.?ffl w\\m GEOLOGY FOR PLANNING IN NORTHEASTERN ILLINOIS II. GEOLOGY FOR PLANNING IN KANE COUNTY Robert H. Gilkeson and Alfred A. Westerman OPEN FILE SERIES 1976-2 Illinois State Geological Survey Urbana, Illinois May 17, 1976 ILLINOIS GEOLOGICAL Prepared for the Northeastern Illinois Planning Commission This study has been financed in part by a grant from the U.S. Environmental Protection Agency under provisions of PL 92-500. The contents do not necessarily reflect the views and policies of that agency. Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/geologyforplanni19762gilk CONTENTS Vol. II, Kane County 1. TABLES AND PLATES I . INTRODUCTION A. Purpose B. Acknowledgements II. GEOLOGY A. Glacial and Unconsolidated Surficial Deposits B. Till C. Glacial Sand and Gravel D. Glacial Lake and Wind-Blown Sediments E. Other Sediments III. TERRAINS IV. NATURAL AND ARTIFICIAL RECHARGE V. DRAINAGE VI. INTERPRETATION FOR PLANNING A. Land Burial of Wastes (including sanitary landfills) B. Surface Spreading of Wastes C. Waste Disposal by Septic Systems D. Application of Fertilizers and Soil Additives E. Application of Herbicides and Insecticides F. Land Utilization 1. Community Development 2. Roadway Construction 3. Open Space Planning VII. NATURAL RESOURCES A. Ground-Water Resources 1. Bedrock Aquifers 2. Surficial Sand and Gravel Aquifers 3. Buried Sand and Gravel Aquifers B. Sand and Gravel Resources C. Peat Resources D. Clay Resources E. Dolomite Resources VTII. UNIQUE GEOLOGIC FEATURES IN KANE COUNTY IX. REFERENCES TABLES AND PLATES (Volume II) TABLE 1: Physical and Mineralogical Properties of Geologic Units Mapped in Kane County. PLATES PLATE 1: Geologic Materials to a Depth of 20 Feet PLATE 2: Principal Terrains PLATE 3: Poorly Drained Soils PLATE 4a: Land Burial of Wastes (Including Sanitary Landfills) PLATE Ab: Surface Spreading of Wastes PLATE Ac: Waste Disposal by Septic Systems PLATE Ad: Application of Fertilizers and Soil Additives PLATE Ae: Application of Herbicides and Insecticides PLATE 5a: Community Development PLATE 5b: Roadway Construction PLATE 5c: Open Space Planning PLATE 6a: Surficial Sand and Gravel Aquifers PLATE 6b: Buried Sand and Gravel Aquifers PLATE 6c: Cross Sections of Geologic Materials PLATE 6d: Shallow Bedrock Aquifers PLATE 7: Sand and Gravel Resources (Including Peat) PLATE 8: Dolomite Resources GEOLOGY FOR PLANNING IN KANE COUNTY, ILLINOIS INTRODUCTION Kane County lies at the extreme western edge of the Chicago Metropolitan area with a total population of about 266,000 and a land area of approximately 522 square miles. It has not experienced the intense de- velopment of DuPage and Cook Counties on the east; however, the eastern half of Kane County, especially along a corridor adjacent to the Fox River, has been the commercial and industrial center of the county for many years and has experienced relatively rapid population growth in the , last few decades. The western half of the county remains primarily rural. Purpose The expectation of continued development in Kane County inten- sifies the need for regional planning. One essential basis for rational land-use planning is a thorough understanding of the physical environment, focusing on the geologic materials themselves. Definition and character- ization of geologic materials is a necessary first step. Then, consider- ation can be given to the interaction of these geologic materials, hydro- logic systems, and potential pollutants generated by man's activity. In addition, it is important for planners to consider the resource value of geologic materials, the natural limitations of geologic materials for various land uses, and natural ground-water flow systems relating to water movement on and through the various geologic terrains. This study includes a map of surficial materials to a depth of 20 feet and a series of interpretive maps made by applying various criteria - 2 - to the basic surficial deposits map. The surficial geology mapping was first compiled on 7V U. S. Geological Survey Topographic Quadrangle sheets which have a scale of 1:24,000 and then reduced to a 1:62,500 scale county base generated by the ILLIMAP system. Various types of data have been utilized for the basic mapping of surficial materials, including field and laboratory studies, logs and sample descriptions of water wells and en- gineering borings, test data from engineering borings, previously pub- lished and unpublished reports, and USDA Soil Conservation Service soils mapping. The series of interpretive maps includes five maps detailing conditions for various waste disposal practices, three maps of limitations for land use, and maps of ground water, sand and gravel, rock, clay, and peat resources. Criteria and methods for both the geologic materials maps and the interpretive maps are described in volume 1. Acknowledgements Numerous individuals have made significant contributions to the production of this report and the accompanying maps: basic geology, sur- ficial and subsurface mapping and soils interpretations, R. H. Gilkeson, A. A. Westerman, K. L. Stoffel, J. L. Phelps and P. C. Reed, with D. L. Gross and L. R. Follmer consultants; waste disposal criteria and maps, K. Cartwright, J. E. Bogner, R. H. Gilkeson; terrain maps and recharge- discharge interpretations, J. P. Kemp ton; poorly drained soils, J. L. Phelps; land utilization, J. E. Bogner and W. G. Dixon; sand and gravel aquifers, R. H. Gilkeson; sand and gravel atid peat resources, J. M. Masters; and dolomite resources, J. C. Bradbury. Comments on the clay resources were provided by W. A. White. In addition, A. A. Westerman, K. L. Stoffel, - 3 - and J. E. Bogner aided in preparing the interpretive maps, while J. P. Kempton and R. H. Gilkeson coordinated the preparation of the maps and report. - 4 - GEOLOGY In Kane County, the drainage, topography, and unconsolidated surficial materials are mainly the result of the action of glacial ice and running water. The layered bedrock lies below these unconsolidated sur- ficial deposits at depths ranging from more than 300 feet (90 meters) along the Marengo Ridge in the northwestern section of the county to less than 3 feet (1 meter) along portions of the Fox River in the eastern part of the county. The bedrock consists of Silurian-age dolomite and Ordovician-age Maquoketa Shale and Galena Dolomite. A detailed description of the geologic units which occur in Kane County within 20 feet (6 meters) of the surface are shown in Table 1. The general stratigraphy and age relationships of both the glacial deposits and bedrock are shown in Figures 1 and 2 in vol- ume 1. The bedrock geology of Kane County is mapped on Plate 6d. Detailed descriptions of the bedrock geology can be found in Buschbach (1964) and Willman (1973) while a summary of the bedrock geology can be found in Willman (1971). Major topographic features in Kane County reflect the influence of glacial deposition. These topographic features include broad, hilly ridges (end moraines), somewhat flat or gently rolling areas (till plains), large knobs of sand and gravel (kames), broad plains of sand and gravel (outwash plains), and the major Fox River Valley, which was a main drainage- way for glacial meltwater and later accumulated sand and gravel deposits (valley train). A more detailed description of the formation of these features and a discussion of the geologic history of the region are given by Willman (1970). - 5 - Glacial and Unconsolidated Surficial Deposits The unconsolidated surficial deposits exert the main physical control on man's activities in Kane County. The deposits are mapped to a depth of 20 feet (6 meters) on plate 1. In the legend on plate 1, the de- posits are described in stratigraphic order with the oldest at the bottom and the youngest at the top. For convenience, Table 1 in the text of vol- ume 1 lists the unconsolidated deposits in alphabetical order. The cross sections on plate 6d show the physical relations of the deposits to each other. In this report, the deposits are described in groupings of similar materials: till, glacial sand and gravel, glacial lake and wind-blown deposits, and recent deposits. The physical and mineralogical properties of geologic units in Kane County are summarized in Table 1. The character of the geologic unit and the geologic processes which formed them are dis- cussed in volume 1 of this report. Till Of the unconsolidated deposits, till is the most abundant and lies within 20 feet (6 meters) of the surface in perhaps 70 percent of the county. Till is unsorted debris deposited directly by glacial ice. It is composed of pebbles, cobbles, and large boulders imbedded in a matrix of clay, silt, and sand. Tills deposited from each of the numerous glaciers which advanced across Kane County have physical properties that make them unique, enabling them to be distinguished from each other. The strati- graphic relationship between different tills are shown in the cross sections on plate 6c. Tills which are present near land surface in one region of the county may be deeply buried under younger tills in other regions of TABLE 1 Physical and Mlneraloglcal Propartlea of Caologlc Unit* Happad In Kan* County Unlta Peyton Colluvlun (pc) Aceratlou-nley (ag) Colluvlatad lichland Loaa. (pc) Crayalaka PaaC ((1) Cahokla AUutIub (c) UctUand Loaa* (rl) ■quality formation Ctnl Maafcar I«i R ■ ■ - qu - w - «d - Cvl - Sd ft ) CI M • I - C-X - MM ounbar of taet* rang* of datai low TaJLua - high vain* Btaabar of blow* per foot (Standard Ponatratlon Taat) uacoaflnad eoaniilvt strength la toaa par aquara foot natural aolatura contaat Is parcant dry danalty In pound* par cubic foot . parcant of gravel In total saapla ■ parcant of aand, allt and clay, raapactlvaly, 1b <. 2m fraction of *aaf>l« parcant ■ontaorlllonlta and axpandablaa In clay fraction parcant 11 lit* la clay fraction parcant chlorlta plu* kaollnlto In clay fraction - 6 - the county. The cross sections also show how the thickness of the tills vary across the county and also show regions where some tills do not occur. Winnebago Formation Tills of the Winnebago Formation do not occur within 20 feet (6 meters) of the land surface in any part of Kane County. Capron Till Member (wic) . The Capron Till is widespread in the subsurface of Kane County, and is shown on the cross sections (plate 6c). It is reddish brown to pinkish gray and is a clayey silt to silty clay till, locally sandy at the top. It probably averages less than 30 feet (9 meters) thick. It is thickest in the northwestern part of the county where it is deeply buried under the Marengo Ridge. Wedron Formation Tiskilwa Till Member (wt) . The Tiskilwa Till is the most regionally ex- tensive surficial deposit in Kane County. The moraine of this till forms a prominent ridge (Marengo Ridge) in the northwestern part of the county. In the morainic area, thickness of the till is commonly greater than 200 feet (61 meters) and locally approaches 300 feet (91 meters). The varia- tions in the thickness of the Tiskilwa Till within the county are shown on the cross sections (plate 6c). Thick Tiskilwa Till is located beneath the Marengo Ridge and in the northern part of the county. The till thins to the south and east and is absent east of the Fox River in the southern part of the county. The Tiskilwa Till is very uniform in its composition and is a reddish-brown to reddish-gray sandy silt till. A large portion of the north-central part of Kane County is covered by an ablation phase of the Tiskilwa Till. These ablation deposits - 7 - are mapped as vt-a on plate 1 and on the cross sections in plate 6c. These till-like deposits are much more variable in their physical properties than the underlying till and may also contain poorly sorted sand and gravel, water-laid silt, and lacustrine or alluvial silt and sand. The ablation deposits are commonly less than 30 feet (9 meters) thick. Maiden Till Member (vm) . The Maiden Till is a highly variable, silty, clayey till which is the surficial material over a large region in south- central and southwestern Kane County. Thickness of the Maiden Till is variable, ranging from 10 feet (3 meters) to 30 feet (9 meters). The Maiden Till is patchy in its distribution and occurs in association with lacustrine silts, alluvial sands, and kamic sands and gravel. Yorkville Till Member (wy) . The Yorkville Till is the surficial material over most of the area in the east-central and southeastern portion of Kane County. It is a silty clay to clay till with an olive-brown to olive- gray color. The Yorkville Till is the finest grained till in Kane County. The till seldom exceeds 50 feet in thickness (15 meters). In some regions of the county, the till is overlain by an ablation phase (wy-a on plate 1) which is gravelly in texture and commonly 3 ess than 6 feet (2 meters) thick. Haeger Till Member (wh) . The Haeger Till is a yellowish-brown, silty, sandy, gravelly till which is the surficial material in the nor theas tern corner of the county in association with thick deposits of coarse outwash. The till varies from 0-10 feet (3 meters) in thickness and forms a discon- tinuous blanket over the outwash. The Haeger Till is the youngest and the coarsest grained till in Kane County. - 8 - Glacial Sand and Gravel Much of the sand and gravel outwaah deposits of Kane County can be stratigraphically and mlneraloglcally associated with given till units. Pro-glacial outwaah deposits which are extensive and continuous In the 4 county are the Haeger Outwash (wh-o) , the Tlskllwa Outwash (wt-o) and the Capron Outwash (wlc-o). The outwashes, as shown In the cross sections, plate 6c, converge In the subsurface In some areas of the county. In the northeastern area of Kane County outwash associated with the Haeger Till occurs at land surface or burled under thin deposits of the till. Where the outwash occurs at the surface It Is mapped as Henry Formation. Arbi- trarily, a vertical "cutoff" in stratigraphlc nomenclature, is made in the subsurface in this area between outwash mapped as Henry Formation and the Haeger Outwash Member. Henry Formation Great quantities of surficial material were transported by melt- water from wasting glacial ice. Different types of surficial outwash are recognized in Kane County according to lithology and mechanism of deposition. The outwash deposits at the surface in Kane County are assigned to one of three members of the Henry Formation. Valley Train Deposits (Mackinaw Member, hm) . The Mackinaw Member consists of sand and gravel outwash that was deposited in valleys of the Fox River and along Blackberry Creek and in abandoned drainage courses in the south- central part of the county. * The thickest deposits of the Mackinaw member are present in the Fox River Valley in the northern part of Kane County. Thickness of the sands and gravels seldom exceed 20 feet (6 meters). Outwash Plains (Batavia Member, hb) . The Batavia Member is composed of - 9 - clean sands and gravels deposited by meltwater on broad plains In front of glaciers. Coarse textured sands and gravels commonly greater than 60 feet (18 meters) thick, deposited In extensive outwash plains are the surflclal material over a large part of northeastern Kane County. The outer margins of the outwash plain converges into the Fox River Valley and the deposits grade into the valley trains of the Mackinaw Member. Areas of northeastern Kane County where the outwash plain deposits thin and the underlying York- ville Till occurs locally at or near the land surface are mapped on plate 1 as hb/(wy). Regionally extensive outwash plain deposits are the surflclal material in the northwestern part of Kane County. However, these deposits are not as coarse or as thick as those present in the northwestern part of the county. Sands and gravels of the Batavia Member are also present in the central, north-central and southern part of Kane County. Here the deposits are thin and do not have great areal extent. Karnes and Eskers (Wasco Member, hw) . Much poorly sorted sand and gravel occurs in high hills, mounds, and knobs deposited by meltwater cascading either off the ice front or into holes and crevasses in the ice. These deposits are kames. Kami c deposits of the Wasco Member occur commonly In the south-central, central, and north-central portions of the county. The deposits consist of hills or ridges that are partly or wholly composed of sand and gravel. The deposits are variable and can be quite clayey and silty. Sand and gravel also occurs in linear ridges deposited by melt- waters flowing along channels either below or within the glacial ice. These - 10 - deposits are called eskera. Much sand and gravel has been extracted from a large esker located along Blackberry Creek In south-central Kane County. Glacial Lake and Wind-Blown Deposits The 8urficial materials of Kane County include sediments deposited in glacial lakes. The lacustrine sediments are predominantly silts and clays and were deposited in quiet-water conditions. These deposits are the Carmi Member (ec) of the Equality Formation. They are yellow-gray to gray, faintly bedded, and uniform in texture. Thickness of the glacial lake silts and clays seldom exceeds 15 feet (5 meters) in Kane County. Regionally exten- sive deposits of the Carmi Member are present in the north-central part of Kane County. When glacial outwash was being deposited, it was subjected to wind erosion. Large quantities of silt and fine sand were picked up and deposited on the uplands adjacent to major valleys. This wind-blown sur- ficial material is the Richland Loess (ri) . The loess is yellow to tan in color, dominantly silt in texture, and is mapped only in the western part of Kane County where it is locally thicker than 3 feet (.9 meter). Other Sediments In addition to glacial sediments, recent geologic surficial ma- terials are present in Kane County. When rivers and streams flood, silt, clay, sand and occasionally gravel, are deposited along the floodplains. These alluvial deposits, mapped as Cahokia Alluvium (c) , which may contain some organic material, are found along many streams in Kane County. Recent sediments are also found in shallow, poorly-drained depressions and along stream valleys where they accumulated as a result of slopewash and other - 11 - downslope gravity movements. Such deposits are referred to either as ac- cretion gley (ag) in Isolated depressions, or where they may grade into predominately organic peat or muck deposits as Grayslake Peat (gl) . These deposits are, Peyton Colluvium (pc) where they Occur along valley slopes and may also contain some organic material. TERRAINS The landscape in Kane County has been subdivided into three basic terrains: uplands, plains and lowlands, listed as A, B and C respectively on plate 2. These terrains were identified on the basis of relative ele- vation, slope characteristics and the sequence and character of the under- lying material. The upland areas are concentrated in the northwestern, central and east-central portions of Kane County. These areas are underlain pre- dominantly by glacial till, the Tiskilwa Till to the northwest, the Maiden Till Member in the central area and the Yorkville Till along the eastern side of the county, mainly the east-central section. The uplands in general are characterized by being the highest features on the landscape. In Kane County they are principally morainal ridges. Slopes ranging from 4 to 7 percent are common and occasionally are found in the range of 7 to 15 per- cent. The upland area in the northwest portions of the county reaches elevations locally in excess of 1000 feet '323 meters) above sea level. This upland is gently to steeply rolling, occasionally very hummocky knob and kettle topography. - 12 - The remaining upland areas reach little more than 900 feet (290 meters) In elevation, the eastern area, underlain by the clayey Yorkville Till, is more gently rolling, with relatively few slopes greater than 7 percent; the central area underlain by the siltier and sandier Maiden Till has numerous, sharp, steep slopes up to 7 percent or greater. Areas designated as plains comprise at least half of the area of Kane County. The principal areas cover the northeastern and southwestern portions of the county with a rather narrow area along the northern portion of the west county line. The northeastern area is underlain by a complex of materials Including fine to coarse waterlaid sediments and till (Tiskilwa ablation deposits), some Yorkville Till and Haeger TL11 and outwash. To the south and southwest, the areas classed as plains are underlain by a relatively thin, locally patchy, blanket of Maiden Till, and occasionally by the underlying Maiden Outwash. The northwestern area is underlain by the Tiskilwa Till on the south and sand and gravel (Henry Formation) to the north. For the most part the plains are flat to gently rolling, generally at an intermediate elevation between adjacent uplands and lowlands. It should be especially noted that the area of the plai is in the northern half of the county are generally higher, about 930 feet (290 meters), than the area to the south and southwest. The plains area in the southern half of the county generally average about 800 feet (258 meters) with a general slope to the south. The lowlands in essence are the principal river valleys of the county including those of the Fox and Blackberry Creek. The Fox River Valley is the principal lowland area although several tributary valleys - 13 - are rather significant. In general all of the lowland areas are relatively narrow with a few areas that are a mile or more in width. The lowlands are mainly underlain by medium to coarse textured water-laid sediments. Al- though the lowlands are mostly flat, with very low gradients toward the south or west, locally the sides may have slopes as steep as 7 percent or more. The most significant lowland area is the north-south trending Fox River Valley along the eastern side of the county. Throughout most of the southern half of the valley in the county the valley bottoms on the Silurian dolomite bedrock. Through much of this the valley is narrow and the immediately adjacent uplands are composed of Yorkville Till. NATURAL AND ARTIFICIAL RECHARGE The Terrain Map, plate 2, shows areas whei e sand and gravel are present in terrains A (uplands) and B (plains). Both of these terrains are potential areas of regional and local natural recharge. They are areas of high hydraulic conductivity (permeability), particularly where sand and gravel is at land surface and relatively thick and extensive. These areas have potential for ground-water development and may be areas where natural recharge may be significant and artificial recharge most practical. Most upland areas are considered to be the principal areas for natural recharge, mainly from rainfall; though slope characteristics and resulting runoff may reduce the overall effectiveness of these areas region- ally. In addition, upland areas which are directly underlain by thick, clayey, relatively impermeable materials (e.g., Yorlville Till) with low infiltration rates, may contribute less regional recharge than some areas - 14 - categorized as plains (area B) which are underlain by extensive sand and gravel. However, the significance of each area cannot be finalized until the entire region has been evaluated. DRAINAGE The soil drainage conditions are major considerations in resource- based planning activities. There are many factors which influence soil drainage in Kane County; such as depth to and fluctuations of the top of the zone of saturation (water table), permeability of the underlying mate- rials, local and regional slope characteristics, and position with respect to local and regional ground-water flow systems, streams and drainageways . Poorly Drained Soils, plate 3, shows aspects of the surface drainage conditions in Kane County. Areas of poorly drained soils were in- terpreted from existing soil maps and areas prone to flooding were taken from flood hazard maps. Poorly drained areas have developed specific map- pable characteristics. These include areas where the soil parent materials are peat or organic sediments formed in filled or partially filled lakes, largely inorganic sediments formed in small shallow depressions, and areas where soils have developed on relatively impermeable materials on nearly flat surfaces with limited surface drainage. In the latter areas, the seasonal rise and fall of the water table, along with periods of intense rainfall, result in periodic standing water in the low areas. During dryer years, these areas may give no surface indication of poor drainage and may be highly misleading to developers. The areas of poorly drained soils also include the many small or - 15 - large drainageways which are local or regional discharge areas and are sub- ject to periodic flooding. Such areas are shown on the U.S.G.S. Flood Hazard Maps (Hydrologic Atlas Series). INTERPRETATIONS FOR PLANNING Waste Disposal and Pollution Potential The maps referred to in this section are intended as a guide for regional planning. They designate areas in northeast Illinois Where par- ticular combinations of earth materials, topography, and ground-water flow systems indicate conditions pertinent to various disposal and land treat- ment practices. By necessity, the boundaries of the areas designating particular conditions are somewhat generalized. Individualized Investiga- tion of any proposed waste disposal site is necessary because of the varia- bility of natural earth materials, limitations of mopping scale, and the erratic distribution of available data. That is, the maps indicate the probability of finding suitable or unsuitable sites within a given area, but they cannot be considered a replacement for incividual site evaluations. In addition, certain considerations (such as distance to nearest well, frost depth, depth to seasonal water table, minor slope variations, areas with potentially variable conditions, or areas near or at mapped materials boundaries) cannot be evaluated regionally but should always be included as part of individual site evaluations. The maps presented here evaluate conditions relative to: (1) land burial of wastes (plate Aa) (2) surface spreading of wastes (plate 4b) (3) waste disposal by septic systems (plate Ac) (A) application of fertilizers and soil additives (plate Ad) (5) application of herbicides and insecticides (plate Ae) - 16 - Designated areas in the five-map series are presented generally in order of decreasing restraints. The main exceptions are areas in which the hydro- geologic system may be a mitigating factor where materials are generally considered unsuitable. For example, several areas along the Fox River would normally be considered unsuitable, where coarse-grained materials with moderately high hydraulic conductivity are present. However, since flow paths are predictable, it can often be shown that the areas of pollution are significantly limited. In addition, proximity to large ground- or surface-water bodies may, in some instances, provide enough dilution of pollutants so that there will be no detectable changes in water quality. Although it is possible to suggest the location of some of these areas, the lack of specific hydrogeologic data renders delineation of such areas on the waste disposal maps too risky to attempt. However, this factor should not be overlooked in the evaluation of specific sites. Any evaluation of the effect of waste materials in certain hydrogeologic environments must also be based on considerations of the number of disposal sites in a given area. Considerations of slope are important to waste disposal maps 2 through 5 (plates 4b-4e). In general, reference to steep slopes in the following sections refers to slopes greater than four percent. Slope was not considered for map 1 (plate Aa) because slope would have to be taken into account in site selection and trench design. It is difficult to show the many areas of slopes greater than four percent and in particular, slopes greater than seven percent. The terrain map should be consulted as to where these slope conditions are most likely to occur while the detailed county soil maps give more precise information on slopes, surface drainage and erodability. - 17 - Land Burial of Wastes (including sanitary landfills) This map (plate 4a) differentiates areas for the burial of all types of waste products in the ground. We have not distinguished the state of the waste product; that is, whether it is solid, semisolid, or liquid. We have included in this map considerations of the burial of both domestic refuse and industrial chemical waste, some of which may be toxic. Areas A through E are listed in ascending order of their capacity to provide pro- tection from pollution of both ground water and surface waters. The basic assumptions are: 1) burial in a trench 20 feet deep, and 2) contact with ground water. In general, the areas with the least limitations (Area E) are the upland terrain areas underlain by either the Tiskilwa Till in the north- western part of the county, or the Yorkville Till in the east-central part of the county. In these areas, the till is greater than 50 feet (15 meters) thick and as much as 200 feet (61 meters) thick or more in some portions of the Tiskilwa Till Uplands. The most sensitive areas for land burial of waste lie principally in and along the Fox River Valley where the shallow bedrock aquifer is at or within 20 feet of land surface and/or whore outwash sand and gravel Is present at or within 20 feet of land surfaces. Other sensitive areas are present in the southwestern part of the county where sand and gravel is frequently present at shallow depths below the Maiden Till, and areas of surficial sand and gravel in the west-central and northwestern parts of the county. Surface Spreading of Wastes This map (plate 4b) differentiates areas where there may be pol- - 18 - lution problems resulting from the spreading of wastes on the land surface or in the top soil. It is to be used primarily for the placement of in- dustrial and sewage wastes, by any method, on the land surface. The solum generally develops sufficient hydraulic conductivity to allow certain amounts of water to pass. In placing wastes on the land surface, the proper application rates must be maintained to prevent overloading of the soil. The loading rates are dependent on the slope, soil types and characteristics. It is assumed in this map that the proper loading rate will be determined; the map separates areas where the practice may fail, areas where extra pre- cautions should be taken, and areas where spreading should be discouraged. It should be noted that Areas A and B are the most sensitive areas with regard to the potential for ground-water pollution while Area C is more sensitive from the standpoint of potential for surface-water pol- lution. In Kane County, the most sensitive areas from the standpoint of potential for ground-water pollution, are along the major drainageways (Terrain C) and particularly the Fox River Valley. Although not shown, narrow bands of Area A occur within Area B along the southern half of the Fox River Valley in the county (see plate 8). However, probably the single, greatest problem for surface spreading in Kane County may be acceptance problems as Indicated by the widespread distribution of Area C. Locally, poor surface drainage (plate 3) and the relatively tight nature of the. underlying materials are the principal factors. It should be noted, however, that within many of the areas listed as C, local conditions may be such that acceptance problems will be minimal for small clusters of Individual systems. - 19 - Waste Disposal by Septic Systems Plate 4c shows the pollution potential of the various materials throughout Kane County. This map does not generally apply to widely scattered, individual septic systems, rather to local or regional concen- trations of individual or community systems. As in the case of surface spreading, the principal sensitive areas are along the Fox River where ground-water pollution potential is high (Areas A and B) and widespread areas throughout the county where there are acceptance problems (Area C) due to poor drainage or relatively imper- meable surficial deposits. Application of Fertilizer and Soil Additives The proper application rates of fertilizer and soil additives should result in their being held in the soil for plant use. Application rates should be adequate to supply seasonal plant needs; this depends upon the character and fertility of the solum. Plate 4c differentiates areas where special care must be taken to avoid excessive application rates. Again, the most sensitive areas in Kane County are similar to those for surface spreading and septic systems. Application of Herbicides and Insecticides The proper use of herbicides and insecticides should result in their being retained in the soil zone. There are few reported instances of ground-water pollution by herbicides and insecticides; there are some reports of surface-water pollution. The glacial till materials generally contain sufficient clay to have a strong attenuating capacity for organic compounds. Herbicides and insecticides generally are immobile, except in - 20 - soils with very low clay contents. Plate 3c differentiates areas in Kane County where special care must be used in application. In general, the most sensitive areas are Area A where sand and gravel are present at land surface. Land Utilization Mapping Both material properties such as texture and bearing capacity and terrain characteristics such as drainage and depth to zone of satura- tion affect the suitability of land for different uses. The engineering properties of mapped surficial materials in Kane County are detailed in Table 2. This table is designed to be used as a broad guide for planning by civil engineers and others directly concerned with the engineering characteristics of materials encountered in a subsurface investigation program. Three maps were prepared (plates 5a, 5b and 5c) to evaluate both terrain and material characteristics for three specific types of land use — namely, community development, roadway construction and open-space planning. Plates 6a and 6b indicate geologic conditions pertinent to community devel- opment and roadway construction. These mapn should be used in conjunction with the USGS flood hazard maps and the poorly drained soils map (plate 5). Plate 5c outlines geologic considerations significant to open-space planning. In plates 5a - 5c, a rigid classification of areas (i.e., good, marginal, poor) was purposely avoided; rather, these interpretive maps should be used as one source of technical input for planning decisions along with other types of non-geologic data. It is assumed that specific construction proj- ects will include an adequate subsurface investigation program. - 21 - Construction Conditions for Community Development Plate 5a indicates construction conditions for community residen- tial development. Major problems in Kane County associated with land use for community development Include poor surface drainage, flooding along major drainageways, and the presence of deposits which have a low bear J ng capacity such as peat or accretion gley. In eastern and northwestern Kane County, fine-grained surficial materials may cause acceptance problems for septic effluents; such materials may also lead to basement flooding when houses are constructed in low, poorly drained areas. In general, plate 5a indicates conditions in order of decreasing restraints to community development; however, note that Areas A, £ and D may all have some potential for flooding along drainageways. Two special considerations are areas of shallow bedrock and loess areas. Areas under- lain by shallow bedrock have both unique advantages and distinct problems. Located mainly along the Fox River and its tributaries, areas of shallow bedrock exhibit very high bearing strengths but are extremely difficult to excavate and do not permit septic system construction. Areas containing wind-blown silt (loess) that is greater than five feet thick are concentrated only in western Kane County. Loess has an unusual internal structure which permits it to maintain nearly vertical slopes when it is dry; however, if it is disturbed while in a saturated condition the structure is altered with an accompanying loss of strength. . Construction Conditions for Roadways Plate 5b Indicates construction conditions for roadways. In general, roadway planners are concerned with locating areas of poor drainage - 22 - and low bearing capacity materials, determining the amount of material to be excavated or replaced In cuts or fills, and locating potential sources of borrow that are close to the proposed construction. Plate 5b generally Indicates conditions In order of decreasing restraints. As detailed In the previous section for community development, major problems relating to construction In Kane County Include areas of poor drainage, areas of low bearing capacity materials, and areas subject to seasonal flooding. However, roadway projects may have sufficient resources for drains, excavation of undesirable material, grade changes, and other remedial measures which are beyond the scope of much subdivision construction. An additional major con- sideration in regard to roadway construction includes loess areas mapped in western Kane County; these are characterized by a very high frost suscep- tibility and may require removal and replacement. Deposits of undesirable 1 organic materials may be avoided, application of load in excess of design load to consolidate material, surcharged prior to construction, removed and replaced, or bridged by deep foundations to higher bearing capacity material. Geologic Considerations for Open-Space Planning Recognizing the importance of open-space planning to an urbanizing area, plate 6c indicates specific geologic considerations pertinent to this type of land use. According to the NIPC Regional Open-Space Plan (1971), the following areas should be given prime consideration for preservation as open-space: i 1. Areas where soils and geologic conditions make them unsuitable for development - 23 - 2. Flood plain areas 3. Areas with potential for reservoir sites 4. Prime ground-water recharge areas 5. Areas with potential for multiple-use planning - i.e., areas with potential dolomite or sand and gravel resources; areas with potential for solid or liquid waste disposal 6. Areas of historic, ecologic, or geologic interest. Plate 5c indicates the mapping criteria that were formulated in accordance with these guidelines. Since planning decisions regarding open space are based on many nongeologic factors, plate 5c does not attempt to outline areas suitable for specific types of open-space use; rather, it gives the necessary geologic input to guide open-space planning decisions. Generally, map areas for resource or waste disposal purposes were rigorously selected from other maps in this series to indicate regions where the prob- ability is greatest that the desired conditions will be present. Note that major areas for resource development and for solid waste disposal purposes tend to be concentrated in eastern and northwestern Kane County. The full range of conditions for resource or waste disposal purposes can be better assessed by consulting the appropriate maps in this series. Areas mapped as G include regions where some of the above conditions are present but where they are less likely to be of major importance . It was beyond the scope of this study to inventory areas currently being utilized as open space or to indicate areas of historic and ecologic interest. - 24 - RESOURCES Ground-Water Resources The sources of ground water for municipal, industrial, irrigation, domestic, and livestock uses in Kane County are the several water-bearing horizons present to depths of 2000 feet (610 meters) below the county. There are five major water-yielding units: sand and gravel aquifers in the glacial drift, the shallow dolomite aquifer (primarily Silurian), the Glenwood-St. Peter Sandstone, the Ironton-Galesville Sandstone, and the Mt. Simon Sandstone. Large supplies of ground water are available at any location in Kane County from the deep sandstone bedrock which is present throughout the county. Ground-water conditions in the sandstone bedrock are described in studies by Suter, et al. (1939) and Hughes, et al. (1966) and are not discussed in this report. Conditions in the glacial drift and shallow bedrock are variable within the county, and large supplies of ground water are not available from these units throughout the entire county. In areas where sand and gravel aquifers are not present in the glacial drift and the bedrock is shale, it may be necessary to finish wells for even domestic supplies of ground water in the deeper sandstone units. Shallow Dolomite Aquifer The bedrock geology of Kane County is mapped on plate 6d and consist 8 of Silurian-age dolomite (S) and Ordovician-age Maquoketa Shale (Om) and Galena dolomite (Og). The most favorable conditions for large supplies of ground water in the shallow bedrock are in the southeastern part of Kane County where the Silurian dolomite is thicker than 50 feet - 25 - (15 meters). The upper part of the dolomite Is usually the most productive because of greater presence of fractures, crevices and solution cavities. The greater the number of such openings Intersected In the well bore, the higher the well yield. On plate 6d the thickness of Silurian dolomite Is contoured on a 25-foot (7.6 meters) Interval. West of the 50-foot (15 meters) thickness line, ground-water yields from the dolomite generally become less as the dolomite thins. Small to moderate supplies of ground water may be obtained where the Silurian dolomite Is thin; moderate supplies are especially possible in areas where the thin dolomite is directly overlain by regionally exten- sive, water-yielding sands and gravels in the glacial drift. The lithology of the Maquoketa Shale is variable in Kane County. In regions where the lithology is shaly dolomite, it may provide small supplies of ground water. Bedrock in the southwestern corner of Kane County is Galena dolomite which may yield moderate supplies of ground water. Glacial Drift Aquifers Sand and gravel aquifers in the glacial drift of Kane County are mapped on plate 6a and 6b and the distribution, continuity, and relationship of the aquifers to other drift materials are illustrated in the cross sections on plate 6c. In this report, a sand and gravel deposit is mapped as an aquifer if it is at least 15 feet (4.6 meters) thick and occupies at least half a square mile in area. Sand and gravel aquifers that occur only at the surface are called surficial aquifers and are mapped on plate 6a. Sand and gravel aquifers that are covered by 10 feet (3 meters) or more of fine-grained material, - 26 - are called burled aquifers and are mapped on plate 6b. Sand and gravel aquifers which occur at the surface In one area of the county may continue Into the subsurface In other areas, where they are burled by overlying materials. These relationships are illustrated in the cross sections on plate 6c. The most extensive surficial sand and gravel aquifers are located in the northeastern part of Kane County (Region A, plate 6a) where sand and gravel deposits are commonly greater than 60 feet (18 meters) thick and locally thicknesses are greater than 150 feet (46 meters). Areas where surf lcial sands and gravels are commonly less than 20 feet (6 meters) thick are mapped as A' on plate 6a. Two factors which reduce the availability of ground water in surficial sands and gravels in the northeastern part of the county are the extensive mining of sand and gravel and the natural drainage of water from sands and gravels present at high elevations along the Fox River Valley. Extensive surficial sand and gravel aquifers are also present in the northwestern part of Kane County (Region B, plate 6a). These sand and gravel deposits are not quite as coarse grained or as thick as those in the northeastern part of the county. Maximum thickness of sand and gravel is over 70 feet (21 meters) locally, with tiicknesses of 50 feet (15 meters) common. The aquifer thins and beocmes less permeable to the west. Areas where the sands and gravels are thought to be less than 20 feet (6 meters) thick mapped as B' on plate 6a. Surficial sands and gravels which are similar in texture but are not quite as thick and do not cover as large an areal extent as those in Region B, occur in the southern part of Kane County in T. 38 N. , R. 7 E. , - 27 - and R. 8 E. , and T. 39 N. , R. 7 E. Surficlal aquifers in this area are mapped as Region C on plate 6a. Areas where sand and gravel is thought to be less than 20 feet (6 meters) thick are designated as C'. Regions A, B, and C contain surficlal sands and gravels deposited in outwash plains and deltas. Elongate surficlal sand and gravel aquifers occur in the east- central and southeastern portions of the county as valley train terrace and channel deposits along the Fox River, and abandoned glacial drainage courses located west of the river. This region is designated as D on plate 6a. Sands and gravels in this region are commonly 25 to 30 feet (7.7 to 9 meters) thick. Areas where the deposits are thought to be less than 20 feet (6 meters) thick are designated as D 1 on plate 6a. Elongate surficlal aquifers occur as channel type deposits on the west side of the county. Sands in this region are, in general, finer grained and thinner than in the other surficlal aquifers. The sands are seldom greater than 30 feet (9 meters) thick and commonly are less than 20 feet (6 meters) thick. These deposits are designated as D' on plate 6a. The distribution and thickness of buried sand and gravel aquifers in the glacial drift of Kane County are mapped on plate 6b. The regional continuity, thickness and relationships of the buried sand and gravel aqui- fers to other glacial drift materials and the bedrock are illustrated in the cross sections on plate 6c. Buried sand and gravel aquifers at least 15 feet (A. 6 meters) thick but less than 50 feet (15 meters) thick are reported in records from water wells and test borings for a large part of Kane County, and their distribution is mapped on plate 6b as Region B. Areas where sand and gravel aquifers of thicknesses greater than 50 feet (15 meters) are - 28 - reported in records from water wells and test borings are mapped on plate 6b as Region A. Areas of Kane County where buried sand and gravel aquifers are thought to be less than 15 feet (4.6 meters) thick or absent, are mapped on plate 6b as Region C. Geologic conditions are quite variable within Region C. Surficial sand and gravel aquifers might be present in the region (see plate 6a) . The region includes areas of thick, fine-grained, glacial drift greater than 300 feet (91 meters) thick, (Marengo Ridge, T. 41 N., and T. 42 N. , R. 6 E.) and areas of shallow bedrock (Fox River Valley, T. 38 N. , and T. 39 N., R. 8 E.). The extensive area mapped as Region C in southeastern Kane County includes shallow bedrock in the Fox River Valley lowlands and thick, fine- grained glacial drift on the uplands. Within Region C discontinuous, buried sand and gravel aquifers may locally yield small ground-water supplies. The cross sections on plate 6c illustrates that geologic conditions related to buried sand and gravel aquifers are variable in Kane County. Section D-D' shows that buried sand and gravel aquifers occur locally above the Tiskilwa Till in the northern part of the county. Thickness of the aquifer is variable but seldom exceeds 30 feet (9 meters). The cross sections show that extensive buried sand and gravel aquifers occur below the Tiskilwa and Capron Till Members. At some locali- ties both of the aquifers are present but are separated by the Capron Till. In a few locations the Capron Till is absent and the two sand and gravel deposits are connected to form one aquifer. This condition may occur along the buried valleys in Kane County. - 29 - Areas in the central and southern part of Kane County mapped in Region A on plate 6b contain sands and gravels deposited in buried valleys. The buried valleys contain deposits of sand and gravel locally greater than 100 feet (30 meters) thick, but the locations of the thickest, coarsest sands and gravels within these valleys is not completely known. At some localities the buried valleys contain thick deposits of fine-grained sands and silts. Silty zones are shown in cross section A-A' on plate 6c. The broad areas in the northern and west-central part of Kane County mapped as Region A on plate 6b contain thick, buried sand and gravel deposits where deposition may have been in outwash plains. The sands and gravels occur below the Tiskilwa Till and have an average thickness probably not much greater than 50 feet (15 meters). Clay Resources Clay mineral and particle size data suggest that Chicago common brick and structural or building tile may be manufactured from the Tiskilwa, Yorkville, and Maiden Till Members and the clayey parts of the lacustrine deposits of the Carmi Member where they are over 20 feet (6 meters) thick (plate 1). These clays, after removing the stones and sand, could be used by art potters. After the same processing as above, the clay could be used in the manufacture of sand size, bloated, lightweight glass balls which can be used in Insulation products. Since large areas of Kane County are underlain by the above mentioned deposits and since there is not thought to be a demand greater than present for such clay products as can be produced from the available - 30 - materials, clay resources do not appear to be a necessary consideration in planning. Sand and Gravel Resources In 1973, Kane County ranked second in Illinois with the production of 5,415,000 tons of common sand and gravel, a quantity exceeded only by McHenry County (Malhotra, 1975, p. 29). Sand or sand and gravel deposits occur scattered throughout the county; however, these deposits vary enor- mously in size and suitability as a resource (Block, I960).. All of the deposits consists of detritus from some closely related stands of the most recent continental glacier to reach Illinois, when water melting from the glacial ice sorted the sand and gravel out of the debris carried by the ice and into the present deposits. Their importance as a mineral resource de- pends on the thickness of overburden, thickness and extent of the deposit, coarseness and mineralogy of the deposit, and the accessibility of the deposit. Common sand and gravel is used as fine- and coarse-grained aggre- gate for concrete and asphalt paving mixtures, base courses of highways, and material for gravel roads, and for ballast and fill. Specifications (Illinois Department of Public Works and Buildings, Division of Highways, 1971, p. 520-542) for sand and gravel to be used in aggregates are more rigorous in terms of proper size gradations and maximum allowable amount of deleterious material than they are for the other uses listed above. The following discussion and the legend of plate 7 lists the various types of sand and gravel deposits in the order of their importance as a resource. Sand and gravel pit symbols on plate 7 include all of those known to be operating or intermittently operating during 1974 (Masters, 1976) - 31 - Each active pit should be found within the quarter section where the symbol is located. A peat pit and several deposits that have some potential as peat resources are also plotted on plate 8, but discussed separately under "Peat Resources." Plate 7 shows the distribution of the sand and gravel deposits in Kane County as presently known, based on the work of Block (1960) and Gross (1969) and that of several Illinois State Geological Survey per- sonnel in preparation of this report. Additional subsurface information was also supplied by the Illinois Highway Department, the Tollway Commission and Commonwealth Edison. The outer boundaries of deposits on plate 8 are taken from the geologic materials map (plate 1) which represents a compila- tion of all data available to a depth of 20 feet (6 meters). Deeper drill hole data is incorporated in the description of the various types of sand and gravel deposits. The most valuable sand and gravel deposits by far are the north- eastern portions of Kane County, in T. 42 N. , R. 8 E. , and T. 41 N. , R. 8 E. (plate 7, deposits I and I,), where coarse sheetlike deposits occur in areas greater than a square mile (2.6 sq. km.). Type I deposits are in excess of 60 feet (18 meters) thick and often have less than 10 feet (3 meters) of overburden. The gravel (commonly 6 inches (15 centimeters) in diameter) in these areas is coarsest to the east where gravel is dominant by weight over sand size (2 mm - 0.62 mm) material. To the west and south, these deposits generally become finer until sand predominates over gravel by weight and most gravel is about 2 inches (5 cm) in diameter, and are designated type I I deposits on plate 8 where they become less than 20 feet (6 meters) thick. Both of these areas have been a traditional source of sand and gravel, and a considerable amount remains for future use if rising property values do - 32 - not preclude their use as extractable resources. Urban sprawl may also prevent development of many areas that are Included In the following types of deposits. Sheetlike deposits that are similar to the above deposits in areal extent but are not as coarse or quite as thick, are present in the north-- western corner of the county in T. 42 N. , R. 6 E. (plate 7, deposits II and II j). The type II deposit becomes thinner and finer grained to the west. Another type II area Is located in the southeastern area of the county (T. 38 N. , R. 8 E. , and R. 7 E.). In these areas, the gravel is generally not over 2 inches (5 cm) in diameter, sand is dominant over gravel by weight, and thickness generally varies between 30 and 50 feet (9 to 15 meters) with only the upper 10 feet (3 meters) or less containing significant silt and clay. Where these deposits are believed to be less than 20 feet (6 meters) thick, they are designated type Hi. Two pits were reported active in the southeastern area in 1974, both in the same quarter section. The south-central, central and north-central portions of the county, roughly townships 38, 39, 40, 41 and 42 N. , all in R. 7 E. , and extending eastward somewhat into the western area of R. 8 E. , contain two types of sand and gravel deposits that are often closely associated with each other, but neither of which have the areal extent of the preceeding types. One consists of sheetlike deposits that are quite variable in grain size and thickness changing greatly over short distances and are designated type III on plate 8. The other consists of hills and ridges that are partly or wholly composed of sand and gravel. They can be extremely variable in content, with large amounts of silt and clay in places, and are designated type IV on plate 1. Where these deposits are believed to be less than 20 - 33 - feet (6 meters) thick, they are designated types III and IV. , respectively. Both of these types of deposits are being worked extensively east of Kane- ville and north of Sugar Grove. Elongate deposits of silt, sand and some fine to medium gravel occur in east-central and southeastern portions of the county as valley train terrace and channel deposits along the Fox River, and several abandoned glacial drainage courses to the west of the river in T. 40 N. , R. 8 E. ; T. 39 N. , R. 7 E. and 8 E. ; and T. 38 N. , R. 7 E. and 8 E. (plate 1, deposits V and Vj). Type V deposits define a few, good, prospective areas that are over 20 feet (6 meters) thick with less than 10 feet (3 meters) of over- burden. However, since they are usually not that thick, the V. designation for thinner areas are more common. Locally, the material probably contains sufficient sand and gravel to support commercial operations. Two operations are reported in this type of deposit in T. 40 N. , R. 8 E. Elongate deposits on the west side of the county, especially T. 39 N. , R. 6 E. , and T. 40 N. , R. 6 E. (plate 7, deposit VI) are also channel type deposits, but consist mostly of clay, silt, and sand. These deposits are generally considered to be less than 20 feet (6 meters) thick. They may contain localized areas of sand and gravel large enough to support com- mercial operations. One operation in this type deposit is reported in T. 39 N. , R. 6 E. Within the thick sequences of glacial deposits in Kane County, there is one large area in the south-central region on plate 8 (T. 38 N. t R. 7 E.) where thick sand and gravel, over 45 feet (14 meters), is deeply buried below 10 to 30 feet (3 to 9 meters) of mostly clay, silt and sand. Its boundaries can only be inferred without a very detailed drilling pro- - 34 - gram. This and other similar deposits, presently unknown, could become important resources as shallower deposits become unavailable. There are too many small, abandoned or inactive sand and gravel pits in Kane County to plot on plate 7. Only the largest areas of excava- tion and fill that are probably related to past sand, gravel, and stone extractions are indicated. In the rest of the county there is much less chance of finding a large sand and gravel deposit than in the areas outlined in the above cate- gories. As more subsurface data becomes available, areas that presently contain the fewest control points are the areas that will be subject to the most reinterpretation. These are usually areas of low population. The most likely type of deposit to be found in the future is additional, deeply buried sand and gravel. Peat Resources Peat is used primarily as a soil conditioner in order to increase organic content, make clayey soil more friable and increase moisture reten- tion. In 1973, only Michigan, of the 22 states producing peat in the United States, out ranked Illinois. Six companies produced 71,552 tons of peat from Cook, Kane, Lake and Whiteside Counties (Malhotra, 1975, p. 35). Currently, peat is being produced in Kane County by Batavia Soil Builders from a location in the S\h SVfr Section 19, T. 39 N. , R. 8 E. (plate 1). The peat is described (Hester and Lamar, 1969) as being four feet thick and composed of about 50 percent sphagnum moss, 40 percent sedges, and 10 percent decomposed organic matter. Chemical analysis indicate a very low 7.3 percent ash content, representing its clay, silt and sand content. - 35 - Hester and Lamar (1960) note a peat deposit covering parts of Section 26 and 27, T. 38 N. , R. 8 E. (plate 8) described in 1922 (Soper and Osbon, p. 105) and presently known as Mastodon Lake on the southwest side of Aurora. Records are not available to confirm it but peat, along with sand and gravel, probably has been produced from this location at some time in the past. The land is now occupied by a high school and a park containing the lake. An abundance of other peat deposits, shown as the Grayslake Peat, are present on the surficial deposits map. The peat layer, as mapped in Kane County by the Soil Conservation Service, U.S.D.A., contains at least 60 percent organic material, the rest being various amounts of clay, silt and sand. However, most of the deposits cover less than 40 acres, are probably less than two feet thick and most likely do not represent econom- ically recoverable resources. Peat in areas drained for agriculture, or similar uses, begins to oxidize relatively rapidly, and becomes a silty, organic soil. Therefore, the above types of deposits can be eliminated as resources in most cases. The few deposits that were not eliminated are outlined on the sand and gravel plus peat resource map as possible resources. These areas are generally larger than 40 acres, and the most recent 7^' topographic quadrangles indicate swamp or bog-like conditions still exist. However, little or no sample information is available on these deposits at this time to indicate whether any of them meet or exceed the quality of peat from the operating pit. As previously noted, the areas containing the operating pit and Mastodon Lake are also on the map. Dolomite Resources Dolomite, a carbonate rock composed essentially of the mineral dolomite, a calcium-magnesium carbonate, is quarried for crushed stone at - 36 - three localities - the Fox River Stone Company two miles -southwest of South Elgin, Conco Western Stone Company at North Aurora, and the Podschwit Quarry of Meyer Aggregate two miles south-east of Big Rock. (Dolomite is commonly referred to as limestone for most commercial and industrial uses and is very similar to it in chemical and physical properties. Strictly speaking, limestone is a carbonate rock composed essentially of the mineral calcite, calcium carbonate.) The crushed stone produced in Kane County is used mainly as concrete aggregate and road rock and as agricultural lirne*- stone. Sources fo dolomite for crushed stone in Kane County are strata of the Silurian-age Alexandrian Series (Kankakee and Elwood Formations) and the Fort Atkinson Formation of the underlying Maquoketa Group of Ordovician age. Fox River Stone Company and Conco Western both quarry Silurian-age dolomite. The Meyer Aggregate Quarry produces from the Fort Atkinson For- mation. All three quarries are rated by the Illinois Department of Trans- portation as capable of producing Class A aggregate, the highest quality of the major aggregate classes and acceptable for use in portland cement con- crete. Chemical analysis (by the Survey's Analytical Section) on samples of the quarry faces at all three operations show that none of the three con- tain high-purity dolomite (more than 97% total carbonates and more than 20% magnesium oxide) such as is used for chemical, metallurgical and refrac- tory purposes. As these analyses are believed to be typical of the quarrable stone resources of Kane County, future uses of stone produced from Kane County quarries should remain much the same as at present, i.e., construc- tion aggregate and agricultural limestone. Plate 8, dolomite resources, shows areas in which Silurian dolomites - 37 - and Fort Atkinson Dolomite are known to crop out. or are present under a thin (less than 50 feet) cover of glacial drift. The 50- foot figure is an arbitrary one, chosen to represent a probable maximum thickness of over- burden that a quarry operator would be willing to handle. Present Kane County quarries have 15 to 30 feet of overburden, and a much greater thick- ness than this would represent a distinct disadvantage to a competitor. Sometime in the future, however, it may be economic to remove greater than 50 feet of overburden because of dwindling recources, advantage of location, or constraints imposed by property availability. Another important point in evaluating the potential of a stone deposit for quarrying is thickness of the deposit. In some areas of Illinois, where thick deposits of limestone are nonexistent, it is common to quarry limestone as little as 10 feet thick. In Kane County, however, as in most of northern Illinois, thick deposits of dolomite are common. While no attempt is made here to recommend a minimum quarriable thickness, it seems unlikely that thicknesses less than 25 feet, particularly under overburden approaching 50 feet in thickness, will be of commercial interest in the foreseeable future. Therefore, the areas outlined on plate 8, in which the stone is less than 25 feet thick, may be of doubtful value as resources. One other qualification, with respect to the map data, relates to stone quality. Although all the areas underlain by dolomite at shallow depth are designated "potentially quarryable," it should be recognized that stone quality may differ from place to place. Thus, the rock at any pro- posed quarry site should be tested for quality before any development plans are carried out. - 38 - Areas of Silurian dolomite deemed potentially quarryable are the outcrop belt along the Fox River, the contiguous strip covered by less than 50 feet of overburden along both sides of the river, and isolated areas elsewhere in the county where dolomite is covered by less than 50 feet of glacial drift. The Fort Atkinson Dolomite is known to crop out or be present under thin drift only in the immediate vicinity of the Meyer Aggre- gate quarry. UNIQUE GEOLOGIC FEATURES IN KANE COUNTY 1. Large abandoned meander scar of -Fox River; Sections— 27-29, 32-34, T. 42 N., R. 8 E. 2. Rock quarry in Silurian dolomite (also others); S\fc Section 3, T. 38 N. , R. 8 E. 3. Large sand and gravel pits which may have special potential for re- clamation efforts; SE*$ Section 13, NE** Section 24 and Sh Section 24, N*i Sedtion 25, T. 42 N. , R. 8 E. 4. Kaneville Esker, most of which has already been removed for sand and gravel. Compare esker on 1929 edition of Geneva 15' quadrangle, where it is a spectacular feature with the remains shown on the latest edition (1964 photorevised) of the Sugar Grove 7V quadrangle. Located in portions of Sections 30 and 31, T. 39 N. , R. 7 E. and Sections 5, 6, 8 and 9, T. 38 N., R. 7 E. 5. Remains of Major Kame, the center of which has been removed by sand and gravel operation near center N^ Section 23, T. 39 N. , R. 7 E. 6. Johnson Mound, a 110 feet high kame included in Johnson's Mound Forest Preserve; NW*s Section 15, T. 39 N. , R. 7 E. 7. Kame Moraine with a number of small hills, probably kames; Sections 2, 3 and 4, T. 39 N. , R. 6 E. 8. Calcareous tufa deposits in Trout Park in Elgin. These tufa deposits occur around springs that are discharging from sand and gravel in the valley wall on the east side of the Fox River. They form soft, semi- friable, porous and spongy, layered surficial incrustations. They are composed of calcium carbonate and show the remains of mosses which are responsible for their formation. Mosses need carbon dioxide to exist and they extract it from the calcium carbonate in the spring water as it discharges. The calcium carbonate is then precipitated as tufa. &i NEJ* Section 1, T. 41 N. , R. 8 E. 9. Devil's Cave, "approximately one mile north of Aurora on the east side of Fox River;" presumably a solution cavern in the Silurian dolomite. REFERENCES Block, D. A., 1960, Sand and gravel resources of Kane County," Illinois: Illinois Geol. Survey Circ. 299, 11 p. Buschbach, T. C, 1964, Cambrian and Ordovician strata of northeastern Illinois: Illinois Geol. Survey Rept. Inv. 218, 90 p. Gross, D. L. , 1969, Glacial geology of Kane County, Illinois: Phd. Thesis, Univ. of Illinois. Hester and Lamar, 1969, Peat and humus in Illinois: Illinois Geol. Survey Indus. Minerals Notes 37, 14 p. Hughes, C. M. , P. Kraatz, and R. A. Landon, 1966, Bedrock aquifers. of north- eastern Illinois: Illinois Geol. Survey Circ. 406, 15 p. Illinois Department of Public Works and Buildings Division of Highways, 1971, Revision of and additions to the "standard specifications for road and bridge construction," adopted 2 Jan. 1971, p. 520-542. Malhotra, R. , 1975, Illinois mineral industry in 1973, and review of pre- liminary mineral production data for 1974: Illinois Geol. Survey Illinois Mineral Notes 62, p. 29. Masters, J. M. , 1976, Sand and gravel pits in Illinois, 1974: Illinois Geol. Survey, open file map and tables. Northeastern Illinois Planning Commission, 1971, Regional Open Space Plan, 53 p. Sasman, R. T., 1965, Ground-water pumpage in northeastern Illinois through 1962: Illinois Water Survey Rept. Inv. 50, 31 p. Soper, E. K. , and C. C. Osbon, 1922, The occurrence and use of peat in the United States: U. S. Geol. Survey Bull. 728, 207 p. Sutter, Max, R. E. Bergstrom, H. F. Smith, G. H. Emrich, W. C. Walton, and T. E. Larson, 1959, Preliminary report on ground-water resources of the Chicago region, Illinois: Illinois Water Survey and Illinois Geol. Survey Coop. Ground-Water Rept. 1, 89 p. Willman, H. B. , 1971, Summary of the geology of the Chicago area: Illinois Geol. Survey Circ. 460, 77 p. Willman, H. B. , 1973, Rock stratigraphy of the Silurian System in north- eastern and northwestern Illinois: Illinois Geol. Survey Circ. 479, 55 p. Willman, H. B. , and J. C. Frye, 1970, Pleistocene stratigraphy of Illinois: Illinois Geol. Survey Bull. 94, 204 p.