DEPAKTMENT OF THE INTEKIOR— U. 8. GEOLOOICAL SURVEY J. W. I"()\VEI,I„ DlUKCTol; THE kmm ELEVATION (IF THE UNITED STATES BY TTTT/NJKY O^ISTN^ETT EXTKACT KKOM THE THIKTKKNTn AXyi^AL HFroin' (iF THE DIRECTOR, 1891-'92 WASnrXGTON OOVKKNMKNT PRINTING (IFFIPE 1.S04 1 i4 DEPARTMENT OF THE INTEEIOK-U. S. GEOLOGICAL SURVEY. THE AVEP.ArxE ELEVATION OF THE UNITED STATES, HENRY GANNETT. 283 THE AVERAGE ELEVATION OF THE UNITED STATES. By Henry Gannett. For several years tlie United States Geolofiical Survey has been en- gaged in the coinpilation of measurements of altitudes of i)oints in the United States, primarily for use as datum poiuts in connection with the preparation of its detailed maps. The results of this compilation have from time to time been published in the form of a dictionary of altitudes, the first edition of which constituted Bulletin No. 5 and a second edition Bulletin No. 76. As a by-product, a map of the United States upon a scale of 0-5000701 or about 40 miles to an inch, has re- cently been published showing approximate contour lines at the fol- lowing elevations above sea level: 100, 500, 1,000, l,.->00, 2,000, 3,000, 4,000, .5,000, 0,000, 7,000, 8,000, 9,000, 10,000, 11,000; and 12,000 feet. From this map has been produced by reduction the map presented in this volume as Plate cvii. These contour lines were constructed from the following material : (1) By reduction and generalization of (iontour maps from surveys upon much larger scales. In the poi'tion of the map contoured by this means the contours can be regarded as correct. The maps thus used are enumerated as follows: The maps of the United States Geological Survey of the Hayden, Powell, and King (Fortieth Parallel) surveys in the West, the Northern Transcontinental survey, the New Jersey Geological survey, and the Minnesota Geological and Natural History survey. These maps suthced to contour the f(»Ilo\ving areas : All of Massachu- setts, Rhode Island, New Jersey, and District of Columbia, western Couuecticut and Maryland, most of Virginia and West Virginia, west- ern North Carolina, eastern Tennessee, eastern Kentucky, northern Georgia and northern Alabama, the southern half of Minnesota, most of Missouri, part of the O/ark Hills of Arkansas, the eastern half of Kansas, central Texas, the mountain region of Colorado, all of Utah, the northern half of Arizona, northwestern New Mexicp, parts of Wy- oming, Idaho, Montana, Nevada, and Washiugton-with northern Cal- ifornia and southern Oregon, besides trifling areas in other states. These areas comprise much the greater part of the mountainous and 284 D. ot 0. GANNETT.) DESCRIPTION OF THE MAP. 285 most difficult regions. Altogether about oue-fiftL of the area of the couutry was contoured by thi.s means. (-) % platting the conn.il.-d iiicasureiirents of altitude uixm maps and sketching contours witli ri'ference to these measurements, using the best available hachure maps as guides in interpreting the measured lieights and in I. .eating contimrs l)et\veen them. Tiiis method, wliich was used in compiling mucli the greater ].ortion of the map, has natu- lally produced results differing greatly in ditterent region.s with the density of distribution of the measurementsof heights and witli the char- acter of surface, whetlier mountainous or plain, and witli the knowledge possessed of the surfiice. About 25,000 measurements of height have been so used, an average, if they were uniformly distriliuted, of about 12 to a square inch of the map. This number of measurements, com- bined with a knowledge of the relief of the country, would be adequate for the location of contours with a liigh degree of accuracy almost any- where in tlie country. They are not, however, distributed by any means uniforndy. A great majority of them are from railroad levels, and consequently the east is much better represented than the west. The level prairies of Illinois are intersected by a perfect network of railroad lines, while in the Cordillerau region, the raih-oads are separated by broad areas of mountain and valley. In this region, however, the d measurements of heigfit is suiipliaiented by baro- metric rn. maiie l)y tlie mmierous exi>l.irations under * "• '•'-' notably that known as the VVTieeler survey, iu>se ctoelleut maps and measurements have been used wherever a\aihible. Theio reintVUi, ii,>,\o\er, cwtaiu areas coucerninc which little information of any kind is to be had. The contoiu-s of the map may be classified with respect to their probable accuracy into four groups. A. Correct. Those areas reduced from contour maps. B. Very nearly correct. The Atlantic Slope, east of the Blue Ridge ; the entire Mississippi A'alley, to the base of the Rocky Mountains and of the Staked Plains; the region of tiie Great Lakes; the valleys of California and Oregon. C. Approximately correct. The remainder of New England, except northern Maine. New York except the Adirondack region. Pennsyl- vania and the Cordillerau region, except the areas enumerated below. D. Hypothetical. Northern Maine, Adirondack region of New York, central Idaho, the Cascade range and the Coast range of AYashington, Oregon and northern California. From the map, the strengtli and weakness of wliicli have been char- acterized above, the areas between the various contour lines have been measured with considerable care up to 10,000 feet. Above tliat altitude the areas are so small in all the States except Colorado, that they have been grouped under the heading " Above 10,000 feet." The results are given below. 286 THE AVERAGE ELEVATION OF THE UNITED STATES. Table I. — Arvim hctwein lAltitudc in feet; States and Territoriea. 0-100. 100-500. 500-1,000. 14,240 1,000-1,500. 1 1,500-2,000. 1 2,000-3,000. 4,400 30,000 3. GOO 6,900 6,000 11,400 610 8,200 3,600 13,800 15.600 700 17,400 35, 200 8.350 11.000 1, 100 1,900 20 44,800 5,900 2,000 150 50 13.880 29, 600 1,230 660 Florida 1 ■ 1 16, 300 5,400 5,800 Uliiioia 11,900 4,700 44,750 28,800 19, 600 8,300 26,900 2 850 35,845 25,900 4,100 78o' 13,900 1.300 19,600 8.000 34,000 14, 720 6.000 7, 400 lU. Sou 2,000 8.400 1,700 6.740 300 1,100 410 Maryland 400 Massacbuaetts 2,000 3,265 1,800 1,150 100 45 700 11 515 1 700 * 10 400 59,365 7 600 Mississippi 4,000 41,510 1.300 1,375 35,600 14, 300 1,000 34.600 24,510 5,400 400 11,700 Sew Hampshire 400 1,955 2.800 2.800 800 4,100 2,100 1.400 215 1,200 1,700 New York 2.400 • 10,900 16. 100 12,500 5,170 18, 700 13 100 10.000 5.800 3.200 12.200 1 000 3 100 North Dakota 25, 300 26, 895 Ohio 760 29, 800 33, 130 10 500 ^ludian Territory i (Oklahoma .* i 1,800 10, 400 9,000 6.500 Oregon 1,700 8,800 9,800 6, 2(10 6.300 6,700 Pennsylvania 600 5,500 12, 700 15. 9(H) 8.215 2.300 470 10,600 650 10. 900 130 8,100 270 South Carolina 90IP 18. 100 70 24. 200 South Dakota 23,000 1 150 Tennessee lo 400 15,800 39,380 7 600 4 900 Texas 23,600 58.400 19 800 ''2 200 44 100 Utah l.OOU 1,965 10, 500 3.600 5.950 2 600 Virginia 9.700 4,700 4 200 6,800 5,000 6, 000 9. 000 18,000 6,000 24, 640 8,000 5 280 4,200 4,800 26.600 Wvoniing 1 199. 790 388. 305 515,770 390. 08U 240,510 262,635 1 ■ ■ ■ 1 ALTITUDES BY STATES. 287 different detfrees of aHititdc. area in siiuarc miles.] 3,000-4,000. 4,000-5,000. 5,000-6,000. 6,000-7,000. 7,000-8,000. 8,000-9,000. 9,000-10.000. Above 10. 000. 12,500 13,600 23,900 10,520 6.100 500 200 14, 000 4.30O 16.500 22, 700 13,500 17, 100 8.30O 12. 725 4,800 13,500 3.400 11.500 1.800 8,600 1,700 12.900 14,500 26. 150 21.900 10, 600 4,540 800 10 . 14,200 180 i 1 i 1 1 7.800 150 * 1 6.000 200 2,650 600 34,200 200 400 31, 280 25. 400 18, 500 4,000 1,400 600 100 1,800 1.800 16.900 5.200 730 211(1 8.000 200 20.100 500 1,800 700 500 180 29,800 24,900 2,000 21, 100 400 15.970 10.800 6,200 2. 800 1,700 600 6.000 1,200 3,300 200 11,100 1,200 500 69 22.000 26.500 23,290 8.600 • 4.100 2,300 182.800 1 263,830 215, 100 159. 515 93.109 ;I9,0U0 19,110 19,200 288 THE AVERAGE ELEVATION OF THE UNITED STATES. From this table it appears that no considerable i)art of Delaware, Uistrift of Columbia. Louisiana or Kiiotle Islainl exceeds 500 feet above sea level: that in fllinois and Mississippi there is no area above 1,000 feet: that in Connecticut, Indiana, Xcw Jersey and Ohio, no part of the surface is above 1,.")0() feet, that the 2, 0011-foot contour is not found in Alabama, Iowa, Maine, Massachusetts, Michigan, Minucsota, Missouri, South Carolina or Wisconsin, the ;5.000-foot in Arkansas, Georgia, Ken- tucky, Maryland or Pennsylvania, the 4.000-foot in Xorth Dakota, Ten- nessee, Vernu)nt or Virginia, the .">, 000-foot contour in Kansas, New Hampshire, New York, Indian Territory or West Virginia. The 0,000- foot contour is the highest represented east of the Cordilleran region and includes no areas of magnitude in Nebraska or North Carolina- The 7,000foot contour overtops the highest areas in Texas; that of 8,000 feet is above the summits of the Black Hills, the highest laud in South Dakota, and above all considerable areas in AVashingtou; while that of l>,00(t feet overlies all considerable areas, so far as known, in Idaho, Nevada, and Oregon. The contour of 10,000 feet is higher than any extended area in Arizona and Montana, while in the States of Cali- fornia, Colorado, New Mexico. Utah and Wyoming, are extensive areas above this contour line. On the other hand, the entire state of Wyoming lies above the contu is not absolutely correct, but, as shown by Mr. Murray (Scottish Geographit; Magazine), it involves no serious error. The areas between consecutive contours were then multiplied by these assumed average elevations, the several products added together, and their sum divided by the total area of the state or country. In cases where the range of elevation is but slight, as in Delaware, Florida, and tlie District of Columbia, the mean elevation was obtained by taking the mean of all measured altitudes witliin its limits. Inas- much as these states are in the eastern half of the country, and the measurements of height within their limits are numerous and well dis- tributed, the average elevations of these states are well determined. Taiii.k II. — Mean elevation. \ State and Territory. Alabama 500 Arizona 4, 100 Arkansas 650 California 2, 900 Colorado G, 800 Connecticut r»UO Delaware ' 60 District of Colnmbia 150 Fl.iiida 100 Georgia noo Idaho 5. 000 niinois 60O Indiana 700 Iowa 1,100 Kansas 2,000 Kentucky 750 Louisiana 100 Maine 600 ifaryland 350 Massachnsetta 500 Michigan 900 Minnesota 1,200 Mississippi j 30O Missouri | 800 Montana I 3, 400 Nebraska 2,600 Feet. State and Territory. Ty > Nevada 5, 500 Xcw Hampshire 1,000 New Jersey 250 New Mexico 5, 700 New York 90U North Carolina 700 NorthDakota 1,900 Ohio 850 Indian Territory Oklahoma Oregon Pennsylvania . . Rhode Island . . South Carolina South Dakotii. Tennessee Texas 1,700 Utah 6,100 Vermont ] 1, 000 Vir;;inia 950 Washington 1,700 West Virginia 1 . 500 Wisconsin ] 1, 050 Wyoming ' 0, 700 United Stales 2,500 Feet. 1.300 3,300 1,100 200 350 2,200 900 From this table it appears that Colorado has the greatest average elevation of all the states and territories. Wyoming follows closely, then Utah, with New Jlexico and Nevada, all of these having an average elevation greater than 5,00(1 feet. 13 GEOL., PT. li 19 II. balfw .