Regional cross Section 6-6 and 7-7 : Southern portion of regional cross Section 6-6 :

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1 Guidebook for Structural transect along Highway 33, Ventura to the Cuyama Badlands, California (April 2, 2017) Leader: Thom Davis, Participants: Coast Geological Society COPYRIGHT 2017 by Thomas L. Davis, Geologist: any commercial use of this guidebook is prohibited without prior permission. Start: 8:00 AM sharp, April 2, Meet at the west end of parking lot behind Century 10 Movie Theater (555 Main St.) in downtown Ventura. Parking lot is downhill of Poli Street and between California and Chestnut Avenues. We will return to Ventura by 4:00 PM. This trip is along paved roads. We will drive to Stop 1 first. Figure 1. Map of a portion of the western Transverse Ranges, southern California, showing cross section lines 6-6 and 7-7 and the April 2, 2017 Coast Geological Society field trip stops. Cross sections are available for download at:

2 Regional cross Section 6-6 and 7-7 : Regional cross section 6-6 (Figure 2A) starts at the eastern end of the Santa Barbara Channel near Port Hueneme, crosses the Oak Ridge fault, the deep Pliocene age sedimentary trough of the Ventura basin, the Ventura Avenue anticline, Sulphur Mountain and Ojai Valley, Santa Ynez Range, Pine Mountain ridge, and ends at the Big Pine fault. The structural interpretation shown in cross section 6-6 is from Namson (1986 and 1987) where it first appeared in publication as cross section C-C (Plate II in the 1986 publication). The cross section restoration is shown in Figure 2B. Cross section 7-7 (Figure 4), crosses many of the same structures as cross section 6-6, and the two sections reveal the variation in geometry and kinematics of the various structures along strike. Cross section 7-7 was incorporated into Namson and Davis s cross section across the entire western Transverse Ranges (Namson and Davis, 1988). A generalized stratigraphic column of the Ventura basin is included at the end of this guidebook (Figure 7). See Dibblee (1982a, b) for additional field descriptions. Southern portion of regional cross Section 6-6 : The southern portion of cross section 6-6 (Figure 3) begins on a structural shelf just south of the West Montalvo oil field which is part of the 60 km long Oak Ridge-Montalvo anticlinal trend. On the basis of the asymmetric shape of the anticlinal fold trend it is interpreted to be part of a north-vergent, fault-propagation fold above the postulated South Mountain thrust. The Oak Ridge fault is the southern boundary of the deep trough of the Pliocene and Pleistocene Ventura basin and the fault cuts the north limb of the anticlinal trend. The Oak Ridge fault is interpreted to be a Pliocene age normal fault whose shallow portion has been rotated northward and into a reverse-fault geometry by folding of the Oak Ridge-Montalvo anticlinal trend. Excess slip from the deeper South Mountain thrust has reactivated shallow segments of the Oak Ridge fault. This structural interpretation can be applied to all of the Oak Ridge-Montalvo fold trend which contains anticlinal oil traps at Sheills Canyon, Bardsdale, South Mountain, and West Montalvo oil fields. Cross section 6-6 shows how convergent deformation within the deep trough of the Ventura basin and along its southern margin is linked to San Cayetano thrust system. Southward directed slip along the Lion Mountain detachment extends across the deep Ventura basin and cuts and translates the shallow portion of the Oak Ridge normal fault southward. Approximately 4.7 km of back slip coming off the Lion Mountain detachment and up the South Mountain thrust creates a thrust wedge between the south-dipping thrust and the deeper detachment. Northward and deeper the 4.7 kms of offset of the Oak Ridge fault creates a structural shelf just below the Lion Mountain detachment and between the two portions of the older normal fault. This structural shelf along the southern margin of the deep Ventura basin and between the offset shallow and deep segments of the Oak Ridge fault is shown in the other regional cross sections by Namson to the east (Davis, et al, 2015). This structural shelf is a regional feature of the southern margin of the deep Ventura basin and extends eastward to at least the Aliso Canyon area of the eastern Ventura basin.

3 Figure 2A. Cross section 6-6 from Port Hueneme to the Big Pine fault (Namson, 1986, 1987). Approximate locations of field trip stops 1-5 are shown above the topographic profile. The cross section shows a fold and thrust belt style interpretation of deformation. Much of the deformation is late Pliocene and Quaternary in age and earthquakes indicate the belt is tectonically active. Figure 2B. The cross section restoration reveals two earlier phases of deformation: late Miocene and Pliocene normal fault movement on the Oak Ridge fault and Oligocene movement on the Santa Ynez fault. Restoration of the section yields 31.4 km of convergence and a rate is km/yr assuming deformation started between 2.0 and 4.0 Ma.

4 Figure 3. Portion of cross section 6-6 across Oak Ridge fault trend, Ventura Avenue and Lion Mountain anticlines and frontal belt of the Santa Ynez Mountains (Namson, 1986, 1987). Geologic unit abbreviations are shown in Figure 2A. Namson s interpretation links deformation across the deep Ventura basin via a mid-level detachment at the base of the Rincon Formation (Tr). Slip on midlevel detachment is derived from the lower splay of the San Cayetano thrust (SCT1). The detachment offsets the older Oak Ridge normal fault, excess slip on the detachment forms a fault-propagation fold (West Montalvo structure), and folding rotates the upper Oak Ridge fault into a reverse geometry. Ventura Avenue anticline results from stacked fault-wedges rooted into the mid-level detachment. The Lion Mountain anticline is shown as a fault-bend fold resulting from a ramp in the SCT1. The Lion fault is shown as a hanging-wall flat developed above the southward-directed fault wedge along the front limb of the fault-bend fold. The cross section crosses the location of the Ventura fault as proposed by Hubbard, et al (2012). Subsequent review of this area reveal no well and fault intersection, well to well stratigraphic correlation, or seismic reflection image evidence to support the presence of the Ventura fault.

5 Stop #1, Ventura Avenue Anticline oil field and Red Mountain fault: Stop is near the axis of the Ventura Avenue Anticline that at the surface has folded deep-marine clastic deposits of the Pico Formation (Figure 3). To the northwest and across the Ventura River wash are outcrops of north-dipping sandstone, siltstone, and shale of the Pico Formation. Further northwest and on the ridge above the Pico outcrops are red beds of the Sespe Formation that are thrust southward over the Pico beds by the Red Mountain fault. The Red Mountain fault is a major east-west trending, north-dipping, reverse fault just north of the Ventura Avenue anticlinal trend. To the north and along the Ventura River course the surface trace of the Red Mountain fault bends northward towards the western termination of the Sulphur Mountain anticline, and the fault s surface trace dies out in beds of the lower Monterey Formation. At the bend Sespe, Vaqueros, and lower Monterey beds dip eastward towards the wide south-limb of the Sulphur Mountain anticline (a smaller anticline on the Lion Mountain anticline). The subsurface geometry and structural cause of this northward bend is poorly understood. Red Mountain fault dies-out in the subsurface before reaching cross section 6-6. The deep Canada Larga syncline separates the Lion Mountains and Ventura Avenue anticlines and along the south limb of the Lion Mountain anticline +5 km of Pliocene marine strata are exposed. Figure 3 shows the Ventura Avenue anticline is a very large east-west trending fold between the Canada Larga syncline to the north and the thick Pliocene and Quaternary age Ventura basin trough to the south. Both anticlinal limbs have steep dips and in map view the north limb has a much narrower north-south extent than the south limb. The anticline has a steep east-plunge into the Ventura trough where it terminates, but to the west the anticlinal structure continues for some distance and, eventually, into the offshore. Onshore the Ventura Avenue anticline traps the Ventura and San Miguelito oil fields. Further westward the anticlinal trend continues and traps oil offshore at three culminations: Rincon (partially offshore), Carpinteria Offshore, and Dos Cuadras (offshore). Ventura anticline portion of regional cross Section 6-6 : Figure 3 shows Namson interpretation (1986) of the deep structure at Ventura Avenue anticline and the anticline s geometric and kinematic connection to the San Cayetano thrust system and the Lion Mountain fault that is exposed along the north flank of Sulphur Mountain. In this interpretation the Ventura Avenue anticline is shown as a detached fold above the Lion fault that is a detachment fault at the base of the Rincon Formation, and also a higher thrust flat to the San Cayetano thrust system. The Ventura Avenue anticline is shown to be folded and uplifted by a series of wedge-shaped imbricated thrust faults that step up from the Lion Mountain fault detachment surface. Under the Canada Larga syncline, that is just north of Ventura Avenue anticline, the lower splay of the San Cayetano thrust (SCT 1) intersects the Lion Mountain detachment to form a southward-directed fault wedge in the front limb of the Lion Mountain anticline.

6 Stop #2, Overview of the Ojai Valley, Topa-Topa Range, Matilija overturn, and San Cayetano fault: Stop is in a large parking area along the northwest side of Highway 150 with an excellent overview of the Ojai Valley and town of Ojai. Adjacent outcrops are Sespe Formation red beds along the north flank of the Lion Mountain anticlinal trend. East of the stop the Lion Mountain anticline plunges eastward under upper Ojai Valley. Small amounts of oil have been produced from sandstone beds in the Coldwater and lower Sespe Formations at the Lion Mountain area located about two miles west of the stop. The south-dipping Santa Ana fault whose surface trace is along the southern margin of Ojai Valley is not shown in cross section 6-6 (Figure 3). At that location the Santa Ana fault is either not present or a very small fault within the Sespe Formation. From the stop, and looking northward across Ojai Valley, is the south flank of the Topatopa Range. The various Eocene formations are overturned to a north-dip with the Oligocene Sespe Formation red beds exposed along the base of the range. This structure is well known, at least geologically, as the Matilija overturn. The Matilija overturn is the frontal structure to the Santa Ynez Mountains anticlinorium (Figure 3). The overturn is the easternmost segment of a steeply-folded panel of rocks that to the west is generally south-dipping. The panel consists of a thick sequence of Cretaceous and Tertiary formations and extends from here to Point Conception (a distance of about 60 miles). Eastward, the Matilija overturn merges into a more complex series of smaller folds: the Echo Canyon and Santa Paula Ridge anticlines, and several unnamed anticlines with overturned south limbs. There the overturn is broken by the San Cayetano thrust which places the Eocene section over Miocene and Pliocene strata along the north flank of the Lion Mountain anticline. As shown in cross section 6-6 (Figures 2A, 3) the Santa Ynez Mountains anticlinorium is asymmetric and south-vergent. The crest and north limb of the anticlinorium are deformed by several small folds and faults that dip steeply to the south. Namson (1987) interprets the anticlinorium as the result of two phases of deformation: one during the late Eocene and early Oligocene (Ynezian orogeny) and the other during the late Cenozoic. The late Cenozoic deformation is interpreted to result from fault-bend folding and fault-propagation folding. The fault-bend fold is related to a ramp in the lower splay of San Cayetano thrust (SCT 1) that extends from the basal detachment at about 12 km depth upward to a higher-level detachment in the Cretaceous section. The slip on the SCT 1 is 17.7 km which is transferred upward and southward along the thrust ramp causing the Lion Mountain anticline. At the top of the ramp is another detachment that is the same mid-level detachment under the Ventura Avenue anticline. The shallower-level fault-propagation fold above the upper splay of the San Cayetano thrust fault (SCT 2) has 3.3 km of slip. In Namson s 1987 interpretation the shallow-level folding has deformed and rotated the older Santa Ynez fault which was originally a north-vergent back-thrust associated with a south-vergent Oligocene thrust system that uplifted the ancestral San Rafael Mountains (Figure 5) (Reed and Hollister, 1936).

7 Regional cross section 7-7 : Cross section 7-7 (Figure 4A) lies about km east of cross section 6-6 (Figure 2A). Cross section 7-7 crosses many of the same structures as cross section 6-6 and comparison of the two sections shows their gross similarity and the geometric and kinematic variations along strike. Cross section 7-7 begins offshore at the western end of the Santa Monica Mountains and crosses South Mountain, Topatopa Range, Pine Mountain, Frazier Mountain and ends at the San Andreas fault (In the Namson and Davis 1991 report the cross section is labeled 6-6 ). Cross section 7-7 was incorporated into Namson and Davis s cross section across the entire western Transverse Ranges (Namson and Davis, 1988). The first structure shown on the south end of cross section 7-7 is the Santa Monica Mountains anticlinorium. The geometry of the anticlinorium is constrained by the surface geology of the Santa Monica Mountains and some subsurface drilling. The fold structure is asymmetric with a steep south limb that is only partially onshore and extends into the offshore. The crest of the fold occurs along the south flank of the Santa Monica Mountains and the moderately-dipping north limb is well exposed along the crest of the range and northward in the Conejo Valley. The Santa Monica Mountains anticlinorium is interpreted to be a fault-propagation fold caused by the Elysian Park thrust (Davis, et al. 1989) which ramps up from a basal detachment at 15 km depth and terminates in an offshore synclinal axis at about 9 km depth. The slip on the Elysian Park thrust is 11.3 km. Within the anticlinorium are several older, down-to-the-north normal faults that probably controlled deposition of the thick section of lower and middle Miocene volcaniclastic and other clastic rocks that occur throughout the Santa Monica Mountains. The Malibu Coast fault is projected offshore into the cross section, where it cuts the south limb of the anticlinorium. The fault juxtaposes contrasting stratigraphic sections: south of the fault the Miocene strata lie unconformably on metamorphic basement rock and north of the fault is a thicker Miocene section as well as lower Tertiary and Cretaceous strata which rest unconformably on metamorphic or Franciscan basement. These relationships suggest that the Malibu Coast fault had older Miocene movement that was down-to-the-north, and had a similar basinal control as the previously mentioned normal faults located further north. The Malibu Coast fault has been reactivated as a reverse fault during late Cenozoic convergence and uplift of the Santa Monica Mountains anticlinorium. The next structures to the north and intersected by cross section 7-7 are a pair of anticlines that include the Oak Ridge-Montalvo anticlinal trend and an unnamed anticline to the south that underlie the western portion of the Simi Hills. The Oak Ridge-Montalvo anticlinal trend is defined by surface geology and subsurface drilling and is asymmetric with a gently-dipping south limb and steeply-dipping north limb. The north- limb is cut by the steeply, south-dipping Oak Ridge fault. The unnamed anticline is primarily defined by subsurface data. The fold has moderately dipping limbs and the crest is broken up by several normal faults. The normal faults are predominantly down-to the-south and

8 control thick accumulations of volcaniclastic and clastic strata. The cross section interpretation shows the two anticlines to be related to ramps on the South Mountain thrust which is a back-thrust off the lower splay in San Cayetano thrust fault (SCT 1). The unnamed anticline is interpreted to be a fault-bend fold associated with a ramp that steps up from a lower detachment at 8 km to an upper detachment at 6 km. The Oak Ridge-Montalvo anticlinal trend is interpreted to be a fault-propagation fold associated with the second ramp on the South Mountain thrust. The Oak Ridge fault is shown as a rotated normal fault that was active during late Miocene and Pliocene time and originally dipped to the north. The South Mountain thrust translated slip up the rotated segment of the normal fault reactivating the fault as a high-angle reverse fault. The slip translated up the ramp for the unnamed fold is 4.0 km and slip translated up the ramp below the Oak Ridge-Montalvo anticlinal trend is 3.9 km. Cross section 7-7 crosses the Santa Ynez Mountains anticlinorium north of the deep trough of the Ventura basin. The anticlinorium includes the structures underlying Sulphur Mountain and the Topatopa Range. In cross section 7-7 Sulphur Mountain lies above the Sisar thrust fault, and the thrust is north-vergent with an asymmetric anticline in the hanging wall. The Sisar fault, which is similar to the Lion Mountain fault to the west, is interpreted to be a back-thrust off the San Cayetano thrust, and the hanging wall anticline under Sulfur Mountain is interpreted to be a fault-propagation fold. At the surface the Sisar thrust is truncated by the upper splay of the San Cayetano thrust system. The Santa Ynez Mountains anticlinorium is composed of several stacked folds and complicated faults that are observed at the surface and encountered in subsurface drilling. The deepest structure is a fault-bend fold that is in the footwalls of the Sisar thrust and upper San Cayetano thrust splay (SCT 2). The fault-bend fold is associated with a ramp in the deeper San Cayetano thrust splay (SCT 1). The ramp connects a lower detachment near the base of the Eocene strata to the upper detachment at the base of the Rincon shale. The SCT 1 cuts and translates the Big Canyon fault and the Oak Ridge fault which are older normal faults. The Big Canyon fault is translated and folded as it moved from the lower part of the ramp onto the upper detachment whereas the Oak Ridge fault is only translated along the upper detachment. Approximately 8.0 km of slip on the upper detachment of the SCT 1 is divided and consumed equally between two back thrusts, the South Mountain thrust and Sisar thrust. The surface geology of the Santa Ynez Mountains anticlinorium along cross section 7-7 (Figure 4A) is dominated by a thick Eocene section that is deformed into an overturned fold in the hanging wall of the SCT 2. This overturned fold is interpreted to be an older fault-propagation fold that has been cut and translated on the San Cayetano thrust system that breaks through to the surface. The ramp making the fault-propagation fold steps up from a basal detachment within the Franciscan basement at about 13 km to the top of the Eocene. The upper part of the ramp has been cut and translated by the SCT 1 and continued slip on SCT 2 fault ruptured to the surface up the frontal synclinal axis of the fault-propagation fold. Approximately 19.1 km of slip has been translated up the ramp on the San Cayetano thrust system. In Namson s 1987 interpretation the Santa

9 Ynez fault is shown to be a late Eocene fault associated with the Ynezian orogeny (Figure 5). This interpretation shows it as a north-verging back thrust from a southverging fold and thrust structure. Subsequent late Pliocene and Quaternary folding in the hanging wall of the San Cayetano thrust system further deformed the Santa Ynez fault geometry. Along cross section 7-7 (Figure 4A) and north of the Santa Ynez anticlinorium and Sespe Creek synclinorium are Pine Mountain and Frazier Mountain. Late Cenozoic uplift and folding of Pine Mountain and Frazier Mountain are interpreted to be related to the Pine Mountain fault. The Pine Mountain fault probably has two phases of movement. The fault juxtaposes the Salinian and Franciscan basement terranes. This juxtaposition must have occurred prior to Eocene time because the Eocene units occur unconformably on both blocks. Late Cenozoic movement on the Pine Mountain fault ruptured though the steep north limb of the syncline to the surface. There is approximately 2.4 km of shortening associated with the blind thrust and fault propagation fold and about 1.0 km on the Pine Mountain fault splay that rupture to the surface. The Pine Mountain fault is interpreted to root into a north-verging ramp on the Pleito thrust system which causes the uplift and folding of the San Emigdio Mountains north of the San Andreas fault and offset of the San Andreas in the deep crust. The relationships between thrusts of the western Transverse Ranges and San Andreas fault were first discussed in Namson and Davis (1988). In this interpretation the San Andreas fault and the thrust systems share a common displacement surface that dips at low angles and offsets shallow and deep crustal parts of the plate boundary. In the big bend segment of the San Andreas fault this displacement surface is a south-dipping fault that has accommodated both right lateral strike-slip on the San Andreas fault and north-directed convergence along the Pleito thrust system during the late Cenozoic. Gravity data and the high topography of the Mount Pinos and Frazier Mountain areas support this model (Namson and Davis, 1988). Fuis, et al. (2012), unaware of Namson and Davis 1988 work, proposed that the San Andreas fault is dipping southwest from degrees along the western big bend segment based on studies of potential field data, activesource imaging, and seismicity. The present-day length of regional cross section 7-7 (Figure 4A) is 95.2 km and the restored cross section length is km (Figure 4B) which yields 33.2 km of convergence. The convergence rate from the western Santa Monica Mountains to the San Andreas fault is mm/yr., assuming convergent deformation started between Ma.

10 Figure 4A. Cross section 7-7 from the western Santa Monica Mountains to the San Andreas fault (Namson and Davis, 1991). The cross section shows a fold and thrust belt style interpretation of deformation. Much of the deformation is late Pliocene and Quaternary in age and earthquakes show the belt is tectonically active. An earlier verison of cross section was used in Namson and Davis (1988) cross section across the western Transverse Ranges. Figure 4B is the cross section restoration. Cross section restoration reveals two earlier phases of deformation: late Miocene and Pliocene normal fault movement on the Oak Ridge fault and Oligocene movement on the Santa Ynez fault. Restoration of the section yields 33.2 km of convergence and rate is km/yr assuming deformation started between 2.0 and 4.0 Ma.

11 Stop #3, Santa Ynez Range and Santa Ynez fault: Stop is along Matilija Creek Road and west of Hwy 33. Good exposures of the Santa Ynez fault occur along the road-cuts. Probable Cretaceous Jalama Formation conglomerate (south block) is faulted against Eocene Juncal Formation (north block). McCulloh (1981) hypothesized that the Santa Ynez fault had 37 km of left-lateral displacement mostly during the Miocene. In contrast Hall (1981) suggested the fault has significant right-lateral displacement during the Miocene. Gordon (1978) and Dibblee (1982) believed the fault displacement was primarily dip-slip and dismissed the large strike-slip displacements as the fault terminated at both western and eastern ends of the Santa Ynez-Topatopa Mountains. Figure 5. In Namson s 1987 interpretation the Santa Ynez fault is shown to have two phases of activity: Late Eocene and Oligocene movement associated with the Ynezian orogeny and late Cenozoic movement associated with the Pasadenan orogeny. This interpretation shows it as a north-verging back thrust from a south-verging fold and thrust structure. Subsequent late Pliocene and Quaternary folding in the hanging wall of the San Cayetano thrust system further deformed the Santa Ynez fault geometry. This interpretation explains the origin of the regional angular unconformity between the upper Oligocene through Miocene strata and the upper Mesozoic through Eocene strata, and provides a structural explanation for the Ynezian orogeny (Dibblee, 1982).

12 Stop #4, Overview of the Sespe Creek synclinorium and Pine Mountain fault and anticlinorium: Stop is along the east side of Highway 33 just south of Sespe Creek (Figure 1). Roadcut outcrops just west of the stop are north-dipping Matilija Sandstone and Cozy Dell Shale along the north limb of the Santa Ynez Mountains anticlinorium. To the north and east is the Sespe Creek drainage. Prominent light-colored sandstone outcrops north of Sespe Creek are Sespe and Coldwater Formations along the trough of an east-plunging syncline. The steeply-dipping north-limb of the syncline is interpreted as a portion of the lower limb of a fault-propagation fold cut by the Pine Mountain thrust (Figure 6). The high ridge above (north) the syncline is Pine Mountain Ridge which is underlain by a thick sequence of Eocene strata in the hanging wall of the Pine Mountain fault. Our location is between the Neogene age Ventura and Cuyama basins. Older rocks exposed along this portion of Highway 33 are forearc deposits predating the Ynezian orogeny and belong to the regional forearc basin that covered much of central and southern California from Cretaceous to Eocene time. San Rafael Mountains portion of regional cross Section 6-6 : Immediately north of the Sespe Creek synclinorium there are two anticlines: one in the hanging wall and one in the footwall of the Pine Mountain fault (Figure 6). The asymmetric, subthrust anticline in the footwall of the Pine Mountain fault is interpreted to be a fault- propagation fold caused by a ramp in a deeper thrust with 3.5 km of slip. This deeper thrust ramps up from an intermediate detachment at the top of the Cretaceous section and terminates in the subsurface at the axis of Sespe Creek synclinorium and within Eocene strata. The Pine Mountain fault is interpreted to be a higher splay that ramps up across the back limb of the fault-propagation fold. The slip on the Pine Mountain fault is 2.4 km. Figure 6. Portion of cross section 6-6 across the San Rafael Mountains, Sespe Creek drainage, Pine Mountain, and Lockwood Valley (Namson, 1986, 1987). Coast Geological Society field trip stops 3-5 are shown above the topographic profile. Geologic unit abbreviations are shown in Figure 2A.

13 Stop #5, Lunch and crest of the Pine Mountain Ridge: Stop is within Matilija sandstone and shale beds along the north limb (backlimb) of the Pine Mountain anticline (Figure 6). The Pine Mountain anticline lies in the hanging wall of the Pine Mountain fault and much of its south limb has been removed by erosion where cross section 6-6 crosses the anticline. Several miles west of the stop the Pine Mountain thrust merges with the left-lateral Big Pine fault (Figure 1). Stop #6, Overview of the Cuyama basin and Badlands, Big Pine fault, and north limb of the Pine Mountain anticlinorium: Directly below the stop is the trace of the Big Pine fault that has had about 13 km of left lateral displacement, mostly during the Quaternary (Davis, et al, 1987). In the distance is the easternmost portion of the Cuyama basin and Badlands. The basin is mostly Cenozoic nonmarine rocks of the Simmler, Caliente, Quatal, and Morales Formations. The nonmarine strata consist of a thick sequence of alluvial fan, fluvial and lacustrine deposits of Oligocene through Pliocene age. To the west is the Sierra Madre which is being uplifted by the southwest-dipping Ozena reverse fault. The hanging wall of the Ozena fault consists of a +10 km thick clastic section of upper Cretaceous through Eocene marine rocks. The thick section is folded, partially eroded by an angular unconformity, and capped by mid-tertiary strata. Left-lateral displacement of 13 km on the Big Pine fault may have offset the eastern Cuyama basin (Cuyama Badlands) from the small Lockwood basin and the Ozena fault from the south-dipping San Guillermo reverse fault (Dibblee, 1982b). Both basins share a similar stratigraphy and history and the Ozena and San Guillermo faults have a similar geometry, movement, and timing. Northern portion of regional cross Section 6-6 : Cross section 6-6 lies several miles east of stop 6 and ends at the Big Pine fault (Figure 1). The present-day length of the cross section is 67.6 km and the restored cross section is 99.0 km which yields 31.4 km of convergence (Figures 2A & B). The convergence rate from Port Hueneme to the Pine Mountain fault is mm/yr., assuming convergent deformation started between 2.0 and 4.0 Ma. Cross section 7-7 (Figure 4A) extends northward to the San Andreas fault and is part of crustal-scale cross section across the western Transverse Ranges published in Geology (Namson and Davis, 1988).

14 Comment on rotation of the Transverse Ranges: Jay Namson and I are asked occasionally about how the large, clockwise rotation of the Transverse Ranges, supported by paleomagnetic data, impacts our cross sections and restorations. There is nothing in our work that supports or denies the rotations, as long as most of the rotation is completed before 4.0 ma. It is curious to us that we have found no structural record of such large-scale block motions recorded in the folds and faults in the cross sections and in the field and subsurface data and mapping used to make the cross sections. Figure 7. Generalized stratigraphic column of the Ventura basin showing ages, stratigraphic nomenclature, rock column, water depth, and tectonic events (Martin Lagoe, unpublished).

15 References Davis, T.L., Namson, J.S., and Yerkes, R.F., 1989, A cross section of the Los Angeles area: seismically active fold and thrust belt, the 1987 Whittier Narrows earthquake, and earthquake hazard: Journal Geophysical Research, v.94, n.b7, p Davis, T.L., Namson, J.S., and Gordon, S.A., 1996, Structure and hydrocarbon exploration in the Transpressive basins of southern California, in P.L. Abbott and J.D. Cooper, eds., Field conference guide 1996, Pacific Section SEPM, Book 80, and Pacific Section AAPG, GB 73, p , Ventura Basin Oil Fields: Structural Setting and Petroleum System, in Guidebook for Field Trip #5, May 7, 2015, Joint Annual Meeting of PSAAPG & Coast Geologic Society, PSSEPM, & PCSSEG, Oxnard, CA 93050, May 2-8, Dibblee, T.W., Jr.,1982a, Geology of the Santa Ynez-Topatopa Mountains, Southern California, in Fife, D.L. and Minch, J.A., eds., Geology and mineral wealth of the California Transverse Ranges: Los Angeles, California, South Coast Geological Society, Inc., p , T.W., Jr.,1982b, Geology of the Alamo Mountain, Frazier Mountain, Lockwood Valley, Mount Pinos, and Cuyama Badlands Areas, Southern California, in Fife, D.L. and Minch, J.A., eds., Geology and mineral wealth of the California Transverse Ranges: Los Angeles, California, South Coast Geological Society, Inc., p Fuis, G.S., D.S. Scheirer, V.E. Langenheim, and M.D. Kohler, 2012, A new perspective on the geometry of the San Andreas fault in southern California and its relationship to lithospheric structure: Bulletin of the Seismological Society of America, v. 102, p Gordon, S.A., 1978, Relations among the Santa Ynez, Pine Mountain and Cobblestone Mountain faults, Transverse Ranges, California [M.A. thesis]: Santa Barbara, University of California, 127 p. Hall, C.A., 1981, Evolution of the western Transverse Ranges micro-plate: Late Cenozoic faulting and basinal development, in Ernst, W.G., ed., The geotectonic development of California: Englewood Cliffs, Neew Jersey, Prentice-Hall, p Hubbard, J., Shaw, J.H., Dolan, J., Pratt, T.L., McAuliffe, L., and Rockwell T.K., 2014, Structure and Seismic Hazzard of the Ventura Avenue Anticline and Ventura Fault, California: Prospect for Large, Multi-segment Ruptures in the Western Transverse Ranges: Bulletin of the Seismological Society of America, Vol. 104, No. 3.

16 McCulloh, T.H., 1981, Middle Tertiary laumonite isograd offset 37 km by left-lateral strike slip on Santa Ynez fault, California: American Association of Petroleum Geologists Abstracts with Programs, v. 65, p Namson, J.S., and Davis, T.L., 1988a, Seismically active fold and thrust belt in the San Joaquin Valley, central California: Geological Society of America Bulletin, v.100, p , 1988b, Structural transect of the western Transverse Ranges, California: implications for lithospheric kinematics and seismic risk evaluation: Geology, v.16, p ,1991, Detection and seismic potential of blind thrusts in the Los Angeles, Ventura and Santa Barbara areas, and adjoining Transverse Ranges, Final technical report, USGS-NEHRP, Award G1687. Namson, J.S., 1986, Cross section C-C Plate II, in T.L. Davis and J.S. Namson eds., Geologic Transect Across the Western Transverse Ranges: Pacific Section, Society of Economic Paleontologists and Mineralogists, Volume and Guidebook 48.,1987, Structural transect through the Ventura basin and western Transverse Ranges, in T.L. Davis and J.S. Namson eds., Structural evolution of the western Transverse Ranges: Pacific Section, Society of Economic Paleontologists and Mineralogists, Volume and Guidebook 48A., p Reed, R.D. and Hollister, J. S., 1936, Structural evolution of southern California, American Association of Petroleum Geologists, 157 p.