The east-west trending Santa Barbara Fold Belt (SBFB) is located on the coastal piedmont of the Santa Y–ez Range and offshore in the Santa Barbara Channel. The SBFB is the westward continuation of the Ventura Fold Belt, both located in the southern part of the western Transverse Ranges. The onshore SBFB is expressed topographically by a series anticlinal hills and synclinal basins. The northern boundary of the belt is the Santa Y–ez fault and the southern boundary is the Santa Cruz Island fault Santa Barbara is located in a zone of relatively high seismic risk.
The principal fault of the onshore SBFB is the reverse-slip, Mission Ridge Fault System (MRFS) is approximately 65 km long, subdivided into geomorphic and structural segments, named the More Ranch, the Mission Ridge, and the Arroyo Parida faults. The tectonic framework of the SBFB consists of three sets of structures: 1) the east-west striking MRFS; 2) northwest striking reverse faults and associated folds; and 3) northeast striking oblique-slip faults that often form segment boundaries of the MRFS.For more information go to: here.
The eastern end of Shoreline Park, provided itŐs a clear day, is a great place to view Santa Barbara Harbor, Stearns Wharf, east sometimes to Rincon Point and even the Santa Monica Mountains. As you look down to the City from the stadium at Santa Barbara City College, which is the last bit of folding of the Mesa, you go into the lowlands of Santa Barbara, which is a synclinal basin. An anticline is a fold shaped like an upside down spoon, a hill like the Mesa. Sometimes they look like a banana split in half the long way with flat side down, as for example Mission Ridge. Turn the spoon right side up and you have a syncline or basin. Folds in the Santa Barbara area form because the land is shortening north to south about one-forth of an inch per year or 250 inches (20 feet) per 1000 years. Over relatively short geologic time of say 125,000 years is nearly one-half mile of shortening, sufficient to form anticlinal hills such as the Mesa or Mission Ridge.
On land, folds forming linear hills or ridges have familiar names such as The Mesa, The American Riviera (Mission Ridge), More Mesa, and Ellwood Mesa, among others. These folds are not static features, but in fact are growing due to earthquake faults imbedded within them that present a potential hazard to us. The areas between the linear ridges are relatively flat lands, but below the flat land are geologic structures (folds) we call synclines, which form basins rather than ridges. The city of Santa Barbara is located on an alluvial fan in one of these synclines, as is the Goleta Valley and the Carpinteria Valley. To the east of Stearns Wharf at the Zoo and Cemetery (two adjacent folds, part of the same general structure), the land gets higher again and you are on the flank of the zoo and cemetery anticlines. Our zoo is on an anticline, providing the interesting topography that houses the animals. Between the Zoo and Cemetery there is a gap through which water from the Andree Clark Bird refuge drains to the ocean at East Beach. Such a gap with a stream in it is called a "water gap". Sycamore Creek where it flows through the Riviera is another water gap. The bird refuge probably occupies a small synclinal basin. Then further east, you go down again to another synclinal basin where the Biltmore Hotel is then up to Ortega Hill (an anticline), down again a bit and up again on Loon Point (an anticline). Thus from Santa Barbara Point, you can see three anticlines in the Santa Barbara area: Santa Barbara Zoo-Cemetery, Ortega Hill, and Loon Point. Along the Santa Barbara coast, if you're on a sea cliff you're on the flank of an anticline. If you're in a low-lying area, you are in a synclinal basin. It's as easy as 1-2-3 to see these folds from Santa Barbara City College or Santa Barbara Point at the east end of Shoreline Park.
When we talk about Loon Point, we are talking about the discovery of the Santa Barbara Fold Belt. Prior to the discovery, it was thought that the elongated hills in Santa Barbara were related to geologically old faulting and erosion rather than recent active folding. Over 15 years ago, while on a field trip to Ventura where the rates of mountain building are much higher than in the Santa Barbara area, Tom Dibblee (a famous Santa Barbara geologist) mentioned casually that the only place he knew of potentially or active faulting near Santa Barbara was at Loon Point, where a small fold and fault occurred. Since we had the time, we stopped at the point.
Walking down to the site, you can see that the topography looks different. You are walking on what is an uplifted marine terrace that should be sloping south a degree or so towards the Pacific Ocean. However, just before it reaches the bluff top at the ocean, it arches up to the south abruptly, forming what we call a fold scarp. A scarp is a slope that is relatively steep compared to those adjacent to it.
There, in the sea cliff, we were astounded to see one of the best exposures of a reverse fault and fold that we could ever imagine. The fault slices diagonally across the sea cliff. Sedimentary layers of the Pleistocene Casitas Formation (about 200,000 to 500,000 years old), and the overlying wave-cut platform and marine terrace which are about 105,000 years old are involved in the folding and faulting. The footwall block of the fault is the lower block (the one you could walk on if the upper block was not there), and the hanging wall is on the upper block (the one you would hang from). The Loon Point fault is a reverse fault, which means the hanging wall has moved up relative to the footwall. The terms hanging wall and footwall come by way of miners who used these terms to describe faults encountered in a mine.
The material being folded is geologically very young and is nearly overturned in places by the folding and faulting. By overturned, we mean that sediments that were deposited horizontally have been flipped like a pancake. Loon Point is important because it serves as a "type locality" for the structures that we believe comprise the rest of the Santa Barbara Fold Belt.
As you stand on the beach looking northward at the fold and fault, imagine what it must have been like before the structure was present. The marine terrace would have been nearly flat, sloping gently toward the ocean. Today, that surface has been warped up steeply at the fault, and you can follow the fold to the east as it drops down below sea level into the Carpentaria Basin. All this folding and faulting has taken place in the last hundred thousand years. To many, this sounds like a very long period of time, but when you compare the time necessary to form mountains, which is often several millions of years, or to the age of the Earth at several billions of years, it is an instant in geologic time. By studying Loon Point carefully, it was determined that the most recent faulting (rupture along the fault plane) occurred in the last 4,000 years. The amount of displacement was several feet, which means it was associated with a moderate earthquake, Magnitude 6 to 6.5. The structure and fault is too small to have produced such an earthquake, but the fault is connected to the subsurface environment, and so the earthquake occurred on a deeper and larger fault, but still caused the rupture at Loon Point.
Chumash People (Native Americans) used tar deposits to help make large canoes; tar was mined here about 1915 to pave the coastal highway; yielded some Pleistocene fossils.
The University of California, Santa Barbara must have one of the most spectacular settings of any university in the world. We like to say we have a beautiful location with beautiful minds. UCSB is a leading research and teaching institution that is world famous.
With two miles of beach mostly at the base of an uplifted marine terrace, but also pocket beaches, there are spectacular views in all directions at UCSB . Before it opened in 1954, the campus was a Marine Corps air base and some of the early buildings from that base are still present on campus.
Uplift of the mesa or marine terrace that the university is constructed on is 45,000 years old, equivalent in age to More Mesa. The More Ranch fault that diverted Atascadero Creek to the west trends from the east to the west through the campus near its northern boundary.
The arrival of the University of California led to many changes of the mesa area from Goleta Point, or as it is often called, Campus Point, to Coal Oil Point to the west. Campus Point is particularly interesting because there is a small, uplifted wave-cut platform at the point that makes a particularly good wave break for surfers, boogie boarders, and kayakers. That is also where Campus Beach is located. We believe that the small wave-cut platform at the point, which is about 6 feet above the presently forming wave-cut platform, is the result of an earthquake, but this is speculative. The setting of the point and the numerous large faults both onshore and in the Santa Barbara Channel argues for an earthquake origin of the rock platform. Nevertheless, the origin of the platform remains in the hypothesis stage. Some of my former graduate students argue that the wave-cut platform at Campus Point is the result of coastal erosion processes related to rock resistance rather than uplift from an earthquake. I can't eliminate their hypothesis any more than I can accept the earthquake idea.
Another interesting feature found on UCSB's campus is the Campus Lagoon . Its long sinuous shape suggests that it was a stream valley that has eroded into the marine platform during the past 45,000 years. This interpretation is essentially correct, but the stream that formed this valley was flowing north into the Goleta Slough. The shape of Campus Lagoon, with its three outlets, looks like branches of a channel system that flowed northward. Thus, the seaward parts of these channels have been eroded away by coastal erosion in the last 45,000 years. Sea levels 45,000 years ago were a couple of hundred feet lower than today, and even given uplift in the recent past, the shoreline was further to the south.
Campus Lagoon is also the site of an asphalt (tar) mine that was located just east of the Faculty Club at the north end of the lagoon. Today, there is a small fence around the pit to keep people from falling into it. The mine operated for about 5 years near the end of the 19th Century. The tar was easily removed at first near the surface because it was hard, but as the pit was deepened, the tar was soft and difficult to mine. Nevertheless, the tar employed about 50 miners and supplied tar to many places in California, including the streets of San Francisco.