UC BERKELEY MASTER NEGATIVE STORAGE NUMBER 03-67.77 (National version of master negative storage number: CU SNO03067.77) MICROFILMED 2003 UNIVERSITY OF CALIFORNIA AT BERKELEY LIBRARY PHOTOGRAPHIC SERVICE REPRODUCTION AVAILABLE THROUGH INTERLIBRARY LOAN OFFICE MAIN LIBRARY UNIVERSITY OF CALIFORNIA BERKELEY, CA 94720-6000 COPYRIGHT The copyright law of the United States (Title 17, United States Code) governs the making of photocopies or other reproductions of copyrighted materials including foreign works under certain conditions. In addition, the United States extends protection to foreign works by means of various international conventions, bilateral agreements, and proclamations. Under certain conditions specified in the law, libraries and archives are authorized to furnish a photocopy or other reproduction. One of these specified conditions is that the photocopy or reproduction is not to be "used for any purpose other than private study, scholarship, or research." If a user makes a request for, or later uses, a photocopy or reproduction for purposes in excess of "fair use," that user may be liable for copyright infringement. University of California at Berkeley reserves the right to refuse to accept a copying order if, in its judgment, fulfillment of the order would involve violation of copyright law. Hart, S. A. The geometrical study of faults and faulting 1911 BIBLIOGRAPHIC RECORD TARGET University of California at Berkeley Library Master negative storage number: 03-67.77 (national version of the master negative storage number: CU SN03067.77) GLADIS NUMBER: 184788210F FORMAT : BK AD:991012/FZB LEVEL: BlLT:am DCF:a CsC:d MOD: EL:7 UD:030604 /MAP CP:cau L:eng INT: GPC: B10: FI1C: CON: ARCV: PC:s PD:1911/ REP: CPI: FSI: ILC: 11:0 040 CUScCU 090 SbDISS.HART.GEOL 1911 100 ‘1 Hart, SS. A. 245 14 The geometrical study of faults and faulting /$cS. A. Hart and L. J. Lathrop. 260 $cl911. 300 10 p. :$bill., map ;S$c29 cm. 500 Includes " map of the Berkeley hills showing the line of this contact as a heavy ink line." 502 Thesis (B.S. in Geology)-- University of California, Berkeley, May 1911. 504 Includes bibliographical references. 610 20 University of California, Berkeley.$bDept. of Geology and Geophysics$xDissertations. 690 0 Dissertations, Academic$xUCBS$xGeology$y1911-1920. 7001 Lathrop, L. J. Microfilmed by University of California Library Photographic Service, Berkeley, CA FILMED AND PROCESSED BY LIBRARY PHOTOGRAPHIC SERVICE, UNIVERSITY OF CALIFORNIA, BERKELEY, 94720 DATE: 08/03 REDUCTION: 10 X Thesis for B. 3. Degree. The Geometrical Study of Faults “..- and Faulting. S. A. HART and L. J. LATHROP. wy 3 - Ww Ph N DIss HART Geol 191) EART THE GEOMETRICAL STUDY OF FAULTS AND FAULTING. A Thesis prepared by S. A. Hart and L. J. Lathrop. 6.5, 219 LIBRARY COPY THE GEOMETRICAL STUDY OF FAULTS AND FAULTING. The methods of Descriptive Geometry are parti- cularly applicable to the study of some of the simpler forms of faults and faulting, and this paper is intend- ed to outline in a general way some of the applications. Classification of Faults. For the purpose of making a study of any fault, it may be classified as: (1) an exposed fault, (2) an obscure fault. The first class would embrace all those direct- ly measurable on some exposed surface such as a quarry face, or by the study of some topographical feature such as the scarp of a recent fault. This class of faults will not be discussed in this paper, except in a general way . The second class embraces all those faults which are hidden in some way such as by a mantle of soil, and can be studied and measured only by making a geological map and working out the various angles and planes by the methods of descriptive geometry. It is this class of faults which this paper is intended to treat in detail, both by means of ideal cases and actual cases of fault- ing in the field. Nomenclature. In any discussion of faults and faulting, it is necessary to define the meaning of the various terms. employed. In this paper we will adopt the nomenclature employed by Mr. H. F. Reed in his paper on the geometry of Faulting, (Bulletin of the Geological Society of America-Vol. 20 , pp. 170-196). The DIP of a fault plane is the angle which the fault plane makes with the horizontal, and the HADE is the angle which the fault plane makes with the ver- tical. The hade is therefore the complement of the dip. The STRIKE of a fault plane is the bearing of the intersection of the fault plane and a horizontal plane. Quoting from Mr. Reed's paper "The names 'nor- mal' and 'reversed' faults will be retained in their or- dinary geometrical meaning without any inferences with respect to the forces producing them". Plate I, shows some illustrations of "normal" faulting and Plate 2, some illustrations of "reversed" faulting. A "Rift" fault such as is shown in Plate 3, is one in which the movement has all been horizontal in the direction of the strike of the fault plane. Again quoting from Mr. Reed's paper "The DIS- PLACEMENT in any direction of any surface-such as a stratum, dike, vein, or old fault, or of any line- is the length of the line joining the separate parts (actual or produced if necessary) of the surface or line, meas- ured in that direction; the PERPENDICULAR DISPLACEMENT is measured at right angles to the surface or line. The OFFSET of a surface is the horizontal displacement measured at right angles to the strike of the surface. For the total movement, we shall use the word SHIFT. The projection of the total shift on a horizontal line parallel with the fault plane, will be called the HORIZONTAL SHIFT; and the projection on a line parallel with the fault plane and at right angles to the former line, will be called the DIP-SHIFT. The THROW or VERTICAL THROW is the difference in altitude of the two ends of the shift, and the HEAVE or HORIZONTAL THROW in the vertical plane at right angles to the fault plane, is the horizontal component of the total shift at right angles to the strike of the fault-plane; it is also the horizontal projection of the dip-shift. The STRATIGRAPHICAL THROW is the resolved part of the total shift at right angles to the strata, or the perpendicular displacement of a stratum.” These terms are illustrated in plates 4, 5, 6, and 7. Plate four is the representation of an ideal fault and Plates 5, 6, and 7 are sections through the block as shown in Plate 4. Ideal Case. Figure 2, in Plate 8 is an ideal representation of how on first examination of three veins A, B and C cut by the same fault A' is apparently heaved to the right C' to the left and B' not at all. If the dip of all three veins was the same, this of course could only be produc- ed as follows; first a movement to the right, before the formation of veins B and C, sufficient to throw A' to the right as far as it is now plus the distance c' is ap~- parently thrown to the left. Then vein C being formed there must have been a second movement to the left, throw- ing A' part way back and C' to the left to their present positions. Then if vein B were formed, we would have the appearance we now have on the surface. But on ex- amination of the dip of the three veins, we see that they vary and we find that it is possible to produce this apparent movement in opposite directions by one movement only. As shown in figure 1, the direction of movement corresponds to the dip of B in the fault plane. The dip of A is less than, and the dip of C greater than, that of the direction of movement, so after faulting we have a result as shown in figure 1, which, after erosion of the higher block to the level of the lower one, be- comes as shown in figure 2. The multiplicity of veins with varying dips in this case, makes a geometrical analysis of the move- ment very simple, all that it is necessary to measure is the dip of each vein-(The dip of vein B furnishing the direction of movement), and the distances A B, B C, A' B' and B' C'. Now plot$ as shown in Plate 9, on a horizontal plane, and a plane in the plane of the fault (in this case taken as a vertical plane). Then draw a line parallel to the direction of movement from the in- tersection of Cq' with the ground line till it inter- sects C . This line ( a ¢ in the plate) is the shift. a b the dip shift and b ¢ the horizontal shift. These values may be checked by performing the same operations with vein A. Faulted contact in the Berkeley Hills. Plates 10, 11, 12 and 13 are the geometric study of actual cases of faulting in the Berkeley hills. This, as well as being a geometric study, serves to il- lustrate some of the difficulties of the field work in connection with such a study. As may be seen from the topographical map, Plate 10, we have a contact between sandstones and cherts situated on a hillside and faulted in two places. At first sight this is apparently an ideal case as having such a difference between the two rocks on both sides of the contact, the contact should be easy to find and having found the contact, it should be easy to measure the displacement. But the hillside is man- tled by a covering of soil, and numerous slides have mixed this soil up and piled it up, in places to a depth of four feet and more. In other cases of this sort, it might be possible to determine the position of the con- tact line by tracing the sand grains in the soil up the hill and calling the point where they stopped appearing the contact line. This method, however, is not possi- ble in this case for two reasons, 1. it is not sufficiently accurate for such small faults as we are dealing with and 2. because of the presence of numerous strata of the same sandstone as the main lower body of sandstone, interstratified with the chert near the contact. So in this case it becomes necessary to dig down through the mantle of soil to find the rocks in place in order to determine accurately the contact line. Our method was as follows: first, a topograph- ical survey was made of the country on both sides of the contact line and a coutour map drawn. On this map we plotted the contact and fault lines. This is shown in Plate 10. Then by the methods of Descriptive Geometry shown in Plate 11, the sections shown in plates 12 and 13 were made. The ground line A A Plate 11, is the line A A in plate 10, the section was taken through the points 4 and 65, and the elevation of the Horizontal plane is taken as the elevation of point 65. The con- struction is as follows. Plot points 65, 50 and 40 - elevations above the ground line and horizontal distanc- es below the ground line, then draw a line connecting v 40 and v 50, and produce it till it intersects the ground line, draw a line connecting v 50 and v 65 and produce to its intersection with the ground line which is at point 65. Produce a line joining H 50 and H 65 to the ground line and do the same with a line joining H 40 and H 50. From the intersection of H 40 H 50 with the ground line, erect a perpendicular to intersect v 40 v 50 this point is VT. Then from the intersect- jon of H50 H 65 and the ground line, erect a perpendic- ular to the ground line to intersect v 50 v 65, this gives VT, and the line joining VT, and V Tp, is the vertical trace of the plane of the contact on this sect- ion as determined by points 40, 50 and 65. From the intersection of V 40 V 50 with the ground line, erect a perpendicular to the ground line to intersect H 40 H 50, this gives H T, and the intersect- ion of H 50 H 65 and a perpendicular to the ground line drawn from the intersection of the ground line and V 50 V 65 gives H Ty. Then the line joining HT, and H Ty, is the horizontal trace of the contact plane in this sect- ion as determined by the points 40, 50 and 65. We then found the horizontal and vertical traces of the contact plane in the section by applying this same method to other points on the contact and then by combining these various traces in a smooth curve, we had the vertical and horizontal traces of contact plane for the entire section. Plate 12, shows the vertical trace of the con- tact plane in the section A A and B B obtained as des- cribed for plate 11. The figures in this plate also show the profile of the hill along these sections. Plate 13, shows vertical sections through the faulte C C and D D. In these figures the upper contact line is a heavy line, while the dotted line shows the position of the contact plane on the opposite side of the fault plane. The profile of the hill was plotted from the contour map and the trace of the contact planes determined by the three point methed of descriptive geo- metry as described for plate 11. Fault C C was entirely mantled by a covering of geil, so it was impossible to get the dip of this fault plane or the directicn of movement, so we have assumed the fault plane to be a vertical plane and the only measurement on this fault which it is possible to get is the stratigraphical throw of the contact plane which from plate 13, we find to be 22.5 feet. While fault D D was exposed enough to get the approximate dip of the fault plane, the contact along the fault plane was so highly weathered that it was impossible to get any indication of the direction of movement, so in this case also the only thing which can be determined is the stratigraphical throw of the contact plane, which from Plate 13, we find is fifteen feet . If it was possible to find the direction of movement in this case, we could find all of the measurements by the methods described for plate 9. i Ve i NORMAL FRULT WITH NO LATERAL MovETENT NORMAL FAULT WITH LATERAL PTOVEMENT THRUST FAULT = NO LATERAL MOVEMENT THRUST FRULT WITH LATERAL MOVEMENT Fa a | RIFT FAULT ~~ NO VERTICAL MOVEMENT. Le TEE E FIGURE A. Ere Bee ee Fre So EE Te A PERSPECTIVE VIEW OF IDEAL FRULT ~ HY Ia = = = = Sn N ; E oP ie RE EE. —— of ——-—-—-—— -* x * X : STRATIGRAPHICAL THROW SECTION THROUGH x, X,XyX, OF FIGURE A = Fle a Er Yu ba LF 4 rie aE FLL Tai THROW boYicl oF Ve IST I HADE OF FAULT PLANE SECTION THROUGH Y.Y, v, (E28 aa iad (fF TSE YY, OF FIGURE A Til i ila Ee rg / : = wo ——————. ——. CE ----—-—- Ee HORIZONTAL SHirT SECTION iV FAULT PLANE OF FIGURE A “h 0 Ada BEFORE Eel =S Td 7% FIGURE 2 PLATE 8 ie: CRE RV ———————— o— — rE EE BY Ee NIE DESCRIPTIVE GEOMETRICAL HNALYSIS OF Cas Tas eR SFT CBT TT bc = HorizonTears Lill ae LATE 8 PLATE © nt gD ir rt tl ai $ ct RR. or CT —————T EL rrctses is yg Pr. af Fe age ety As shocu sg Fhe Line 'S Cor foeF ar Gf eary Wed SOAP . C. BERKELEY LIB ne PAT. JULY WZ 0 FR: E IMPROV N32) COLUMBIAN CLASP ROCKVILLE CONN. 3 WORCESTER.MASS. HOLYOKE,MASS. 32” SPRINGFIELD.MASS. HARTFORD.CONN. WAUKEGAN.ILL. Lrcsed is 4 pap of Fhe Rel, ely As Sshocussg Fhe Line o 'S Corr m0 F ax Gs cary Wed SOAP LIBRARIES COkL71b692kL0 "PAT. JULY WE (ELE THE iMpROVED (AN COLUMBIAN CLASP / WORCESTER.MASS. HOLYOKE,MASS. ROCKVILLE CONN. : SPRINGFIELD.MASS. HARTFORD.CONN. WAUKEGAN LL. PLATE NO. /0 CONTOUR MAP Sowing Linveor ConTac 7 bd Larhrap Ei S.A Hor” Sca/e~/=230" i Ap 1 1 | Ij, 2 LR ER : J a sul el st toot, 6 [8 [2 Jo | 2. joe J i i tH 4) 4 FT. i at pL i= td 1 TPA | I 6 Hi 2 AL 1 I o [Pp NAL 4 1 2 [THT | "gl 2 FT 1, 2 1 yl 1% 3 |e m Hi 2, lo, ; 8, {i 16, et bil 8/1 alt, It oft PLATE MNO. /2 5% TRAE Bs Hn 2| | 1 FETT lo 3 [TT TTT TIT TT 1] 2 I dn ae I JE a AH bike wT ini Cas | aE vik y HEI Ad’ AEE Pe La rid - Wp ————— — v 4 : ] iil hi Ent TENGE Ett ei, A PH 1 PLATE NO./3 ER PTTL TI TET 2] 2 3 lis 4] 2 5 mn 1,00. |6, [8 | Ldbidiiid) Ll fH LITH. BRITTON & REY. S.F. = rt —t BER AN Mar } a SR 3 . : — aad ® WE RT a us END OF TITLE