The Santa Susana Thrust Fault and its Related Problems: a Progress Report Citation Sutherland, John Clark (1929) The Santa Susana Thrust Fault and its Related Problems: a Progress Report. Bachelor's thesis, California Institute of Technology. doi:10.7907/BSKP-3P23. https://resolver.caltech.edu/CaltechTHESIS:12152009-112122931 Abstract No abstract. Item Type: Thesis (Bachelor's thesis) Subject Keywords: San Fernando, Santa Susana, Piru, Santa Paula, Hueneme, Calabasas, Triunfo Pass, Santa Susana thrust, Oak Ridge Mountains Degree Grantor: California Institute of Technology Division: Geological and Planetary Sciences Major Option: Geology Thesis Availability: Public (worldwide access) Research Advisor(s): Buwalda, John P. Thesis Committee: None, None Defense Date: 8 June 1928 Additional Information: Supplemental Files Information: Topographic Map: Supplement 1 from "The Santa Susana thrust fault and its related problems : a progress report" (Thesis). Date(s) Collected: 1903. Geographic Location Bounding Box: -118.5 Degrees East; -118.65 Degrees West; 34.33 Degrees North; 34.25 Degrees South. Photograph showing Aliso Canyon: Supplement 2 from "The Santa Susana thrust fault and its related problems : a progress report" (Thesis). Panorama looking north up Browns Canyon: Supplement 3 from "The Santa Susana thrust fault and its related problems : a progress report" (Thesis). Record Number: CaltechTHESIS:12152009-112122931 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:12152009-112122931 DOI: 10.7907/BSKP-3P23 Related URLs: URL URL Type Description https://doi.org/10.22002/D1.511 DOI Supplement 1 in CaltechDATA: Topographic Map https://doi.org/10.22002/D1.512 DOI Supplement 2 in CaltechDATA: Photograph showing Aliso Canyon https://doi.org/10.22002/D1.513 DOI Supplement 3 in CaltechDATA: Panorama looking north up Browns Canyon Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 5446 Collection: CaltechTHESIS Deposited By: Tony Diaz Deposited On: 11 Jan 2010 18:46 Last Modified: 03 Oct 2019 23:44 Thesis Files Preview PDF (Thesis) - Final Version See Usage Policy. 3MB Preview PDF (Topographic Map) - Supplemental Material See Usage Policy. 5MB Preview PDF (Photographs) - Supplemental Material See Usage Policy. 2MB Preview PDF (Photographs) - Supplemental Material See Usage Policy. 1MB Repository Staff Only: item control page

THE SANTA SUSANA THRUST FAULT AND ITS KBLATED PROBLEMS A PROGRESS REPORT. J, Clark Sutherlana Submitted to the California Institute of Technology as a Thesis for the Bachelor of Science Degree, June 8, 1928. TABLE OF CONTENTS, I Introduction - - (fie Summary - - Geography - - Stratdgr aphy - 2opanga formation Modelo Formation Saugus formation Structure - . Regional structure Local structure Economic Geology - ILLUSTRATIONS. Cross-bedaing in the Saugus formation Cross sections ~ Landslide at the head of Browns Canyon Santa Susana fault contact at head of Browns Canyon - Panorama from the Williams oil well 13. 13. 17. 256 ll. le. LS. el. In envelope in the back of the Panorama looking north up Browns Canyon - Aréal map of the area, report, INTRODUCTION. The results of pievious geological investigat- ions of this area are found in tne U.8.G.S,. Bull- Previous work etin # 691 "Structure and Oil Resources of cne Simi Valley" by Wm. S. Kew and in uU.S.G.S, Bulletin #753 "Oil and Gas Possibilities of Ventura end Los an- geles Counties" by wm. S, Kew. — the work that. Kew N carried on consistea of: mappthe the major portions tay oi the aréa covered b; the San Fernanuo-Santa Sus- ana-Piru-santa Paula and the northern portions of the Hueneme-Triunfo Pass and Calabasas shects. The work was done under the auspices of the U.S, Geoligical Survey and, in as much as the Survey was primarily interested in the economic poss- ibilities of the region, Kew mace no attempt to work cut complicated structural relations. lt was for the above reasons, coupled with the fact sg, that tne writer could; £ tne m map, fhe aided) in * nh idem sc ake. bere can _— his inexperience with’ the formations “involved” that Professor John Peter siwalda sugested the Purpose Of panta Susana thrust Fault to the autnor as a work problem for his thesis for the pachelor of science begree fiom the Ualifornia Institute, The work was started about the tarst of: the storrnny cL ASA fi y year of 1928 and this paper. oe ars on tne writer's arogress on the partial; solution ot the proolLesn at tuc uate of writing, tne miaule of may. tat j ent une sum: (OL they tiela uayS Spent in tnis are. Time Sp ng amounts to ebout tive weeks, The writer wishes to acknowleage with part- . ; . ook yp . Acknowledge iculer emphasis | the great nelp and time thet ments br. Euwalda has so willingly sccorued in clarifying tne writer's hazy notions. To my fellow stucents at tne institute nan, thanks are aiso aue. fhe Santa susana initust is a Med OF gts ucke ure in the Santa Susana- Vek nlage voast hoange. A movement of several miles as occured along the fault in which the northern over-riding ‘Hee olock hes aadéd many thousands ot fect to the N scdimentary section of the region, pot thé | structure Las an exposed length of about twenty miles. its eastern end «as been rmimatid ty ansthnr. ~ Ae Taulted/so that the ‘true*termination is not OK visible in the fiela. Folding of the favlt sur- Tace mas also occuried. the age of the thrust teulting is probably early or midule rPléistocene, GKOGRAPHY. wt The Santa psusana thrust is a etructure t:.at . o Location tenas B.N.K. enu wnose trace 1lges in toe panta pusana ona Vek Hiage mountains. tae torust b.ock is north of une trace, it Guns @acrOss pahta pusanu A - ana part of whe Piru quadiangles, the dist&nce 2 Length from ome end to ne other is about <0 miles ina » ememnarosont Lea neat A lien NRE HO OO etralght dine, ihe area studicd in this report cove:s the trace of the fault, ana such eeructures Scope of r rt aajecent to che sault GH coed to have bearing Po on the thrust, tron Los ange les- -ventura cow“h ne north of the town of Santa, Supana to tne eage of lewis’ the pantea ousana she.t 5.8. cI mission Fkoint. | Gisead cThe Major portiong>ot whe western part of the area aw Accessabil - Shine within veapy biking distance / fo y, vhe 10ads es, ity léad up brown's vanyon. uvhe public is wi owen to permission must be gained in oraer to go up Limekiln and Aliso canyons. A new real eatate sub-division with its attendant good roaas lies just south of the most eastern portion of the area. (CONDITIONS. — PHYSICAL FE A TYRE These are numerous springs along the fault from which highly mineralizea waters, containing t Water ' - 7 - much sulphur come. However, tney lose their Supply objectionable taste Ae a few minutes of flow uown stream. | San Fernanuo, Simi, and Santa Clara valieys lie ut anewevation of about 1000 feet,bne Santa Relief Susans mountain 1idge lies at about 5400 teet average ¢levation, Thus the relief is about «400 re about 1700 feet A feet. Within the areas studied, ‘exists. Streams in the area that flow into the Simi ana Sunta Clara valleys gain airect access westw Drainage ward to the sea. Those that go into the San f#ern- ando valley eventually arcin into the Los Angeles River to the southeast. Sandstone formations in the area usually Vegetation support a brushy growth, particukarly on the north siae of the hills. The brush in the canyons is often impossible to penetrate. Shale members of the form- ationBasreuuspally covered by grasses and wild oats EXposures of the fault in the canyons are Exposures very good. Cn the spurs, the Moaello shales of the over-riding block have slid down over the fault trace and have obscured the contact in many places completely. ne recency of tne movement along tne fault is/s’ The recency 6 I a g cc Contre] of shown by the fact that the etructure of the hills present phy siogr- is still :eflectea in the present topography, a apny spy the remarkable phenononen for the naj ori th of struct- he ype ee ures in the Céelifornia Uoast Kanes. they i ae Pp avet doe be AYfountcah To the north of the fault trace are to be founa many elevations aoove 3.00 ieet, some of . 2 SAAT them attaining 3600 feet, (nis souta of tne fault / no é€levations a1e to ve found higher than <700 tect, this, ana the fact that the trace is : . de Reh always on the south side of whe riage, jaaxes the author, velieve iat the overthrust structure has had some control of the topography. An old ercsion surface is to be seen in tric Cycles of erosion viru sheet, a table lend with a mature topogra hp on ots top and with a topographic unconformity on each side lies north of the town of Santa Susana. Tie eviaences of this cycle of erosion are not nearly as clear on the east siae of the Sant Susana Pass, Tuere are some evidences of tnis cycle in the long gently sloping riages which, when one is above them, can be easily coriélatea into tans which are now dissected, This probably represents a partial cessation of the uplift of tne ridge ana then a renewed uplift as Lepr@sentea in the renewed power of the streams. STRATIGRAPHY, Femnbins Topanga ,(Miuale Miocene ) This formation consists mainly of weil beaded . tan ana brown coloiea sandstone contcining large rouna concretions and minor thicknesses of conglom~ _ OF trad, crate, Upon weathering, the sandstone vecomes mottled in places and is seen to be very irregul- ee wena kL arly vedded, Hard uark brown concretions are ef ten> id found, Apparently imbedded with the sandstone are ~~ ” Cpnatibaacl” ‘layers of soft brown fine grained sandstone which Fett dembh apparently graue upward into the woaelo shales. The Topanga is cut oy a a greet many aikes and uaS8 a great many Flowsqinter beaded with it, that Intrusive are) of a quite ‘basic character, A badly weatherea andesite or basalt Mass occurs in the Topanga at the head of Srown's Canyon. The material has the following charactcristics:- It is a dark green finely c1iystalline rock with no phenocrysts. The main distinguishable minerals are olivine ana norgpblenae, although this aetermination is aiffieult due to the alte ~~. eration of the rock, It is occasionally filled with amygaules of calcite, opal, and ,very infrequently, zeolites, The author ’ regards the) maternal M an inter- nell 4 fail, the beaded flow for the following reasons, -+et,The matcrial has a very regular thickness for over ae fr Ay one mile of 00d exposure’, Gnss\fnis in sheet is extremely improbable in a sandstone form. ation, 2fia> 4 end, The material appears to be perfenti. conformable with the beds of sanustone, However, its a parent lack of vischcularity _ ; . go: 2 AL ot and other eviaencés of flow structure gaace rardt Afthrntines ; acct lGon€. ~ obstacles in the path. of this view, the extreme pathy are weathering is probably aue to the action of waters linaahatid bib. : , . . . ws tine. SF perculating aown through the fault-brecciatea formations. Fossils are common in certain norizons/of tue Fossil Topanga. ‘ine fauna of this area resembleSin many —— correlation ways the fauna of the Temblor formation of San Vv Joaquin vailey. The Topanga outcrops in .nis area at the nose of the thrust at brown's canyon. Exposures Ww A thickness of about 50 feet overlaid by the —- Modelo ana unuerlait” by the basalt flow which lies — on the fault contact ,is exposed at the head of ) Brown's Canyon, It again outcrops below the Moucejho and above tne fault surface in the vivinity of Aliso Creek in the eastern part of the area, Mouei fo Formation (Uyper Miocene) In genelal, the lithology of the Mou-1fo is oe . Lithology fairly aistinctive so that it cah oe Easily separated from the other formafions. 1t is composed, »rimerily, of shale, within which are several large ienses of coarse sanastone, ancgin tne castern vortions sometimes conglomeratéd. > lhe shale of vhe uodelfo is mainly of an ; Shales argillaceous variety containin.j a considerable percentage of organic matter, Ge eres surlaces, “— its color is a Gark bluish gray to black, but it weatners to light gray or buff color and Tlorms a orownish soil. When fault-biecciatea, it turns a uarKk brown on the surtace, which is in marked contrast to the usual light tan. The sanastone is Sanastones rather coarse grained, in some places congiomeratic, Clay shales, particubarly, where the sanastone greues into tne shale are interbeuued in tuin layeis with it. in color, the sandstone is ordinarily voromn tan or buff, though a aark brown is by far the most common in this area, In the castern portion of tnis area, the uou- Differences in formation éljo contains comparatively little shale, being — within area composed largely of conglomerates ana sandatone, 70. SAUGUS FONMATION. The Saugus. formation is a great series of unlithified sand, giavel ana clay. its physical features indicate inat it hes a marine origin ana was formed close to shore. peut tas anu whalevones (ture sh anetetet nn Fartner wv. the cast, Lt gradua.ly Mer.zes santo a at dived aut Cerne: terrestrial ucposit proovably tormea by a sinking in ecneral, the saugus formation is unilorm Li thology in lithology, consisting mainly of iight colored gravel ana sand, usually more o1 less consolidatea With interbedded lenses of soft fine sandstone and brown well-cemented conglomerate, The formation contains cross-bedaing in many ,»laces. For the most pait, the beas are unfossiliferous although certain horizons contain a great many inverteorates. A Lew scattered whaie bones were tound by the writer. & partial section of the Saugus formation in Brown's Canyon gives some iaca of its nature in this area, | Heptresentat- ive section Upper member of gravel and light colored sand which is in the main unfossiliferous except for very infrequent whale bonesS- ----.- ----25-.0 io0' Yellow or buff-colored sand stone and conglomerate with light colorea fine sandstone lenses in which some cross-bedaing is found Very fossiillerous, one 5' cea c4nacoding alost co1t@) she ile emer ert nat eee 190! Af. g *% | J ee a i 4 2 g 2 ¢ MEL aL AA &. gl ic xy i syal oe SECU o ial t otal par CROSS SECTIONS Vertical and horizontal scales - = - - 2 inches-=1 mile This is two times the scale of the accompanying map. (R. G egind chord ras on this aha 1, taf hdr repel ate. ¢ cto . SF. STRUCTURE. 5 2 f which tne Santa Susana ana . The coast Tange 0 c & a an Regional — “ Oak Hidge mountains aie a yvart, is an general characterizea by shoit lenghh\ structures nat have rwrnnernenecer en gg ao ft a general airection of east and west: Pi ovably / if tue two latgest structures in this area aie the / na@ppy vamp Syncline end the Santa Susana thrust dautt (me “ The thrust, according to Kew's map, iuns “ 4 Purallelism imatel liel to tue San uaoriel ho of the proximately p € .€ San Gabriel ana aJp aleiy para O Us en wa € , i Santa SuB- then mérges into it in a vertical system of ana & San Gabriel faults faults called by Kew tne “sierra Miaure wauuits", atte _ oF San. i ; é mt: f Toe western ends of the santa Susana and “Le ptwdtnn ban vabriel faults, in sudition to che/Yarallel- — is & parently a normal fault in this region and ce, Men. | it may” be: possible that this tault system may be rae the compensating factor that thrust tauiting Ym whe ths, theoretically requires, That is, it may paitially ae 0 tiud yt or wholly make up for the shortening of the crust da aah otha? by the thrust. Liund-sliading is very prevalent in the region, Tne badly faulteshattered seuiments, which often Landslioing contain much heavy material in the shape of conglomeratic boulaers, scem to(landslice very casily. Along the thrust tnis is particularly true, apparently because of the heavy decd weight of the well consoliaated Modelo shales. The shales have been badly shatterea oy the thrusting, and consequently, ofter no resistance to gravitational stresses. A rather strixing featu:e concerning tne nature . . . . _ Relative of the thrusting is the relative incom etence of incompetanc to. of the Mod- the tso ITormations, sicvuelo shales anf Saugus con- elo and Sa . og i . Saugus glomerate, involveu in the actual uifitrential formations movement. in the normal case, che shales veing well consoliaatead, hera, brittle, ana mainly siliceous, should sutfer less than the more recent ana less consolidatea Sc«ugus formation, In the fiela ofl,vhis area, however, tne opposite is (the tiue pictues Tne Saugus shows comparatively litthe deformation in contrast to the brecciation jf the ivauelo, in the thrust fault zone in which aifferential movement oetween Scugus ana woaclo has occulred, Zone of _ breccition the «odelo usually nas gv to 150 teet of b.aly viegciated material which looks as though it haa oeen churned over and over. wo trace ot the orig- inal bedaing is to be found. unis zone usually stands out oolaly in the fiela as a sharp vegetationless step running around the topyograph,. Its coloration is a dark redaish brown. The eviaences of the fault in the fiela as Evidences of one approaches the actuul contact are: the fault ist. Overturning of the nanging wall foimation «ag one ayproathes the fault trace. anu, Brecgiation, siickensliding, OM" go 4 oA benavmne! “ Sra. ag roy the formations involved, that is, goers kilove> seugus. ees TW: ty be Aart Ber deen Oo Aa, 4tn., Markea unconformity.—~~ hem ye e. as ae al need tne east Wake LE A Rk 76. . Log eke peewee Overturning of the formations oi ihe over 1 +t ioe JE. Oy /f overturn i1iaing block is not a general case ana seems to f 0 t 1ng of modé@lo a ibd 6 adh at fault be Limited to a snale“Comar atively Massive céua- “A anf conicct. itnmat is, overturning wus Clearly shown in the sodelo shales above the tault shen tue shales weie aciuail; cut by the fault and the Seugus formation formea the ; cD vtom Ssuriace or the gliaing plane. wnen Topanga was Tauited against beaugus, V-ry Lli.tle eviuence of tiue overturning Was observed in cither tne ioOpango, beusus,ior / ‘Modelo sha.e section, When toe tault trace tan ee thi ougy. the Mouélo weial€ ocuutun, uo overturns ing wes observed either above o1 below the Y Ari at. § Cc ak, bin s fairly age of fault y the fact that the overricing thrust s closed) p! nee Tne age of tne fault is block rests on the Saugus formation, br, Stock Zé ave ag his ‘Binion that the Saugus is late Pilocene or even early Pleistocene in uge. As some Dive to ten thousand feet of seuiments neve been strip»pea off the overriaing tlock, the age a7 _ wo gar SE tmmmena of tne movement is Pscistocene in all probability Lower ov micele,. The total movements, vertical and horizontal, Total were not measured by the writer aue to the lack of Movementey time anu the aifficulty of fincaing «& place where the sections coulda be meusured., Probably the best plece for this task would be on the north side of the Senta Susana Mountaing where the seaiments are AAG ed daic out in .egular orger. .ne thickness of format- ny) lons vary greatly in t Ao: ~ . ary greatly in the Coast nenges trom place fe 17 to place but this is Ne eset ybace “a aa ae to wany ihetid ‘ thousenug vf feet ond the Lorizontal to quite & nun- » tywdowes far Uns armed, oti Ucr of miles. Since whe over tha ueting, the Tault plane has 4, AA leemominige 8 COA hb enpdicdl, been tolced and faultea to. a ‘major aegree, &e Wil. ( we shown velow, Lup Tne Santa Susana thrust, appar.ently, naé head Lite fg kneels ee f Divergent Wicel uiver nt aips. sccoruing vo Kew's map, tue dips of vereent a44 : es the fault aips long | whe fault) vary fiom o uegreces at the nose of che fault «et brown's canyon to Gu Géegréecs at the Ait east ena of the fault. Tne writer cémits that the Gips along tne Leault ao vary consiaerably but he Goes not believe that iney have such wiuely oivergent aips as »ostulatea cy Kew, The writer otfers us an alternate weory, that it may be possible that at ULe castern ena of ihe thrust, tne fault plane may have been cut off by @ vertivel tault which makes the thrust seem to merge into a vertical system. Local The structuie on che Aliso venyon (west) structure if highly complicated. The Williams anticline, which is continued westwaid una whose axis is a . Western inaicateéa on the map, runs uncer the Senta Susana portion of area. overtnrust una changes ihe vip of .he plane from about £5 uegiees on €ither side of tne “nose” — to about 5 degrees on the nose itself, This anti- cline is further war ,ed so that a aistinet WOME , as clearly chown vy outward dips on ail siaes of tne Aa MAA ahegid 4 47 eXis,’lics et the heaa of Aliso Crek(west) noith west #) of the williams oi] well, A variation of che usual Asda on, we Wouela overriuing Saugus formation is to be founda on the west clue of the nose in wnoich the unacrlying Topango end Mouelo shales ale exposea unacr the fault trace, the writer experienced no w.icvtsg ulifticulty in uctermining the cause Lor the discre ancy of th & Gips in the fault plane in the vicinity of tne nose, Thelé are, .€ verieves, two possible explanan- ations to account fol the ,.enomeria: 1, lendsiiciang to tne south may have carried ihe Fault tiace uownwara from its true original position so that the lesser aips aie obtainea. as has oveen mentioned oefoie in this report, leana- sliuing is very near Le in this aiea. however, ee ttre Divides several wiffi ulties(arése, to this toeory; the A we a, ae whe ad adients eradient aves not appeur steep enougn to give tne ae Cheer a! necessary 1orce to bring this slicing about, altho the force .cula be comparatively low aue to the nature of the lozecing of the baugus by the neavy shales and une fault breccliation cf the 1tegion. anotricr objection to the landslide theory is tne total lack of topographic expression of the sliae. ..ecent siiaces are usually shown oy ‘unconformetablé Copograpnie™ 1d tuck . : “ arainage. pda, of seagiuents toweras the Gtripped> at tg Mek. deg it rd é hil¥ is ‘ano. ber is another criterion for the uetermination of dandsliaig. Tne nita & ine southern tip of the nose woes —™ not have aly) g1eat break in slope. Ine dips in the —- bacly fauit shettered formations ao not seem to indiceteCuny tilting, A «. Warping of the fault plane by folaing aiong Lhe Williams anticline. his anticlinel structure nes ad strong Toloing int Lhe Suugus ana has ploocxnoly toluedy #2 Some ut lee hue pout “ylenes, This conuition is not surprising when one stops to consiuer the ra,iaity in which ueformation has been taking place in the voust hanes botn in ine immediate geological va st, (anu at present. The actugtl relations along tne fauit at ti.as point are, in the main, 1ather obscwe uue ee ete ab. Aang to Uae Bire a cetri tus f1det ingy contact. Gooa exposures are to be found on UOWN ,OVEr Ue cliher side of the nose at the head of beown's Cenyon anu aliso van;on una at the tip of wine nose only. At the tip of the nose, the thrust nas Sierra Madre(#) been cut off oy a verticel fauit whose differ- fault ential movement fas sesultca, further west along the fault, in the Cretaeeous Cnico beas on the south being faulted inl) uxteposition a with nocene Méeganos beds on the north, This fault, the writer aa is a continuation fat. of the Sierra tear @, sy stem ana it will be so aésignated in this report. ihe exact amount of movement of the Sl¢éira Maare(?) tault «at this point, in which the southern block sas risen) the writer wes unable to Saige: Ake Se es OO : A great many lanaslices of the side walls of Brown's Canyon occur near the heac of che Zo stream. The creek hes incised ratner ceeply Gin? the softer rliocene veus in comparison to the rather flat-e-topped souclo riuges. nt the heaa of siown's canyon, the usuai Head of 4b Browns “oaclo shale contact at tue fault is uisplaceu Canyon ~y a small thickness of i panga formation which has been faulted against tre Suugus. in the Topanga formetion at the actual fault trace, « clystalline muss of basalt or andesite occurs. A Comprehensive aGiscuss.on of his mass wos given unuer stratigraphy of ihe liOpango. AS a glance et the map will show, the o.tcrop of this mass is limited to this one locality within tue al Ga, the Sierra Maare(?) favlt continues east- wera from che nose, although the eviaence of tue fault is not co clear,uue to ine fact that Lhe same formation, fue baugus, is to ce founu ~~. on both gides of tne fault. However, the shar p saddles, the. canyons: which run. in. the:.wrecciavea fault zone, line up with one another, and so the writer teels safe in pargy ine une fault u, i ENA to the point to. where it ung) under the acluviunm, In the vicinity of Limexiln canyon, ise . ; Limekiln thrust occurs at tre surface in the sioueélo shaic:s Canyon | DAB hb its trace is ¢0 Of éniefly, (Fecognitedyby the bie. clatead zone described above, uhe writer was again able to get a dip of the fault end measurea it on the cast sice of the canyon as Photograph taken in Browns Canyon of the Topanga- — flow-Saugus contacts, The Modelo shales lie just above, The detritus of the shales as shown in @ manner which brings out the dig@ficulty of accurate mapping of the fault contact without actual outcrops in the area, ZL Z 2. about 5 or 6 uwegrees to the north. however, if ; ; Seg +s , te steepens somewhat in the vicinity cf sliso UrecKk Eas orn portion pen of aréa (cast) where the alp asounts voCalmost> 55 or 40 Geprees. vat this point, it is ciosély agsoc- latcea With i.wo other faults wh. ch Lie immeuiate- ly to the south of the thrust. The first one to the south may be co:rélateu with the thiustin,y ( sulting but it seems to be much more reasonauly explained as a step lault in tne fairly large vertical movement «iong ine Pauilt to the south, fhe most southern of tnese three faults emerges A eneath dppriten abel, from uncer the ailuviun avout on « line with — piibiontth. ghuirre., the so cai:led Sierra Maare(?) fault of which \ the-writer spoke-above. its uwirection of parce . et cere nn movenent ig the seme and eo the writer céelieves that ti.is teult chould be aiso / cailéa the Sierra Madie:?) fault. rhis zone of movement merges into ihe pleria jinaie system tory Vy ge or : . Lo tne cast. oe sierre Madre? : , aa fault The nature of the tovements elong the sitira madre (?} fault ere ovnly inaicated sy urag Lolding in the Moaelo shales north of the contact, ana in ihe saugus on the south, nis, of course, is a poor criterion cut the writer wishes to -oint out tne following fects. ist. ine shales are exposea for about 100 yas. im one place lying almost flat anf sowing little ueformation. as one a; proaches the feult, the shales graaually take on a gieater and ,-reater Uip to the north. . uduey 7 Aaa wrtadg (age 1 asad z S. Fh, end, asicve from tins oxég Gulcing, very iittle aeformstion is to be seen, If the movement haa been Oscillatory, we wou la expect to find such more crumpling. Indistinct anu yet ieirly acfinite olag i8 ulso to be opserved in the Siugus, pointing to the same direction of movement. whese cri.eria are stiengtrened oy the diag on the auailiary fault to the immediate north. The grag in the shales on the south block, the Mat A ate, sandstones cn the north block again point to EL Lat. Sikiwect the seme nature of muvement in wiiich the cecona fault is but &@ secona step. ine thrust teult north of these faults seems to dip about 355 or 40 degrees. About one mile to the cust of the canyon, Discussion 1 of the Santa all usree of the faults seem to merzc, (togetheD . Suaana - . ee Sierra Madre? the writer vcelieves that tne tbielra Meaie(?j) | fault relat- Taults have cut off the Santa Susana tirust ody Ons UpWara or aownwara movement on ime south sice of the Sierra Madie(?} system, Ine cutting off by erosion of the top of tue south clock woula remove the plane of the thrust irom this block, further ervsion snmoulad expose ine fault relations on the nortn block shen the land surface becomes lower then cne s.uthernmost pert of tne thrust plane, One other solution to the problem of the CVV hd ttn ab. A i¢lations in the fiela 1reseins to be, Spoken “ots if the so-callea Sierra adi CPfeult movement Zt had hadYits main Girection the dropping of tne southern block, ine same result ».oulc be obtained, ihe movessent, in this hy othesis, wouluw have to be large enough to oring the Suu,us of tue over siting clock in guata,osition with tne .icaelo shales cf wne same unit. ine vide celt of alluvium of the San rernanco velley woula hide the thrust fault trace wnat woule erop out on the southern olock, This last theory is more in accora with the natuwe of tne movement of tne sierra Madre «ana San Georiel faults to the east in which there has been large uplift of the northern block, however, shear faulting in which there has been reversal in ulrection of movement along a tault plune is not uncomnon in the complicated geology of the Uoast hange. 7 aS, x CUNCMIC GEOLOGY. AS in most of the cocst :anges of the south- cin part of Celifornia, che nain €conomi ced” int- erest is in the petroleum ossivilities., wita tne exccption of a few »ravel pits ana a small reasting iurnace where tie shells of an : , a gs a ; PA Liat, Abetno caxtiemely fossiliferous pea .f the Seyus Lourii- ade x gation ale burned to meke lime foi tocal use, the main economicgL activity of a geological — nature has been in tse seerch for petroleum. wuite @ numderoi wells have been arillea in this area, most of them quite a nupber of [Pgh % years ego in the vain s.arch itvi oil. Only one 24 ell, tne Williems well, woose location Russel-Williams — _ oil well is shown on the map, is now being orilled., inis well is aown avout 4300 feet. ne arillers pessed through a gas sound at 1500 fect ana,at present, their main activities are confined to an effort to cut back to that level in an enaeavor to obtain the gas for fuel purposes, the well is located just south of the axis of the williams anticline and tne conuitions are fairly fuvoi able for a .rodauction of petroleum a Possibilities of except ror wne fact that tue .egion is so beauty Petroleum proguction cut up by faults. it seems improbable that tne oil would have founda any barrier vnich would collect tne liquid in this badly shattcred area, it is a vely peculiar tect that no 01] has ever been found on ine north sice of ben wernanuo valley. nome tuctor, cither .ne Enormous uiunocer oF major feulvs to oe Louna in tuis region or some Oiner clement tuat muvVel is bie LIViLE aAsvwaii peobbem of the Menner OF pevtroicum colicection nas entered into this case, we.