The sunshine. The surf. The culture.
San Diego is an attractive location to tourists all over the worldand to people who live in the region because of what it offers:world-renowned theme parks, beautiful beaches, strong businessopportunities and a melting pot of diversity.
The geography of San Diego helps make this area so desirable.People can waterski in Mission Bay all year long or spend a quietevening looking at the city lights from atop Mount Soledad. Familiescan play in the surf on Coronado Beach, then drive over to the otherside of the peninsula and watch boats sail into the deep-water bay.
But how did the terrain of San Diego develop?
San Diego’s geological history is the subject of a new film,titled Written in Stone: The Rise and Fall of San Diego, created bySan Diego State University geology professor Patrick Abbott,Television Production Supervisor David Graves and several students.
The video explores how land tilting, the Rose Canyon Fault and therise and fall of sea level played into the formation of the region.It is separated into three acts and explains how several processesmingled to form some of San Diego’s greatest geographical jewels.
Abbott hopes the video will be the first in a national televisionseries that uncovers the geology of several cities in the UnitedStates. It will also be used as a teaching tool in classrooms.
The video’s history lesson of San Diego begins about 1 millionyears ago — when all of the city west of Interstate 15 was underwater.
“Everything you think of as San Diego today was beneath theocean,” Abbott said.
Land in the eastern part of San Diego began to rise and,consequently, the ocean began to retreat west. The exposed oceanfloor became the San Diego people know and love today.
As the sea retreated, it carved canyons and valleys westward.After millions of years, the runoff of rainwater from the upliftedland cut through these canyons, producing perfect locations for SanDiego freeways. Interstate 8 and Highway 52 are examples of roadwayscreated from these age-old riverways.
The video also delves into how fault lines have played asignificant role in the formation of San Diego.
In Southern California, there are many active faults across theland — the San Andreas fault system is one of the more famous ones.
The Rose Canyon Fault system affects San Diego the most. It startson the east side of San Diego Bay and travels north through La Jolla.When it hits the coast, it runs offshore for about 65 miles until ithits land again on the curving California coastline.
Over millions of years, pressure built up until it was releasedand earthquakes occurred. The shakes pushed the shoreline out intothe ocean, and the La Jolla coastline was formed.
The fault, which curves to the left near Highway 52, is alsoresponsible for creating some of the highest and lowest points in theregion. Over time, earthquakes caused the fault to move, forcing theland to squeeze upward, creating Mount Soledad. In other places, thebends caused the land to pull apart and sink, setting the stage forthe formation of Mission Bay and San Diego Bay.
Why should San Diegans today care about the fault so much? In1933, its northern end near Long Beach caused a 6.3 magnitudeearthquake — the second deadliest quake in state history.
The video also shows how the rise and fall of the sea levelchanged the makeup of San Diego.
About 14,000 years ago, glaciers covered the northern part ofNorth America and the sea level near San Diego was 400 feet lower.During a period of natural global warming, these glaciers melted andthe sea level rose to its current position.
Incoming waves from the northwest hit the California beaches at anangle. Wave after wave deposited tons of sand southward along thecoast. After many years, this created Mission Beach.
After the glaciers melted and the sea level rose, San Diego’sshoreline looked like one big bay with three surrounding islands,formed by land uplifted from the Rose Canyon Fault system.
So, how were these islands connected to the mainland?
The ancient Tijuana River helped create Silver Strand, whichconnects Imperial Beach with Coronado. Over the years, flood seasonsdeposited millions of tons of sand and mud into its delta built outinto the ocean.
Hurricanes in the Southern Hemisphere created huge waves thatpicked up and redistributed the sand deposited from the river. Asix-mile barrier grew until it connected with Coronado.
The formation of the Silver Strand in the south and Mission Beachin the north trapped water from escaping to the sea, thus creatingSan Diego Bay and Mission Bay.
“A lot of people think we dredged (Silver Strand) up to create thebay,” Graves said. “It’s not true. It was just nature.”
Point Loma was similarly formed.
Today, Point Loma lies where the mouth of the San Diego River usedto rest. Over time, the river dumped massive amounts of sand onto itsdelta. That delta grew until it connected the island to the mainland.The formation of that landmass helped separate San Diego Bay fromMission Bay.
Today, San Diegans call the area at the base of Point Loma theMidway District. It houses major structures such as Lindbergh Fieldand the Sports Arena. Also, all sewer pipes from the city cross thesediment to a treatment plant on Point Loma.
The problem with this area is that it is made of loose sand dumpedby the San Diego River. If the Rose Canyon Fault sends another majorearthquake toward the city, its inhabitants may be in trouble.
“The land is stable for day-to-day life — yes, but not verystable during a big earthquake,” Abbott said.
If a major quake occurred, the land in this area may liquefy andcause serious damage to the structures. If a large number of sewagepipes broke, sewage would be spilled into Mission Bay and San DiegoBay.
The film’s creators are not worried about that right now. Abbott,Graves and SDSU students Robin Thompson and Eddie Bororquez are nowputting finishing touches on the 30-minute video that has taken ayear and a half to write, film and produce.
The no-budget film is Abbott’s brainchild. It is taken out of thefinal chapter of his book, The Rise and Fall of San Diego, publishedin 1999. In early 2000, he decided to take the black and white pagesand transform them into a three-dimensional project.
Abbott wrote the scientific explanations and Graves broke themdown into laymen’s terms. The students helped create graphics andillustrations.
The video made its world premiere in October to an audience at theSan Diego Natural History Museum and exit polls from the eventindicated the audience liked what it saw.
This excites Graves and Abbott, who are currently searching forfunds for the next two videos in the potential series — Los Angelesand Austin, Texas.
The creators said they will also enter the film in the EmmyAwards, under categories for science education.
“We gave ourselves to this project — spent a lot of our own timehere late at night,” Graves said. “We’ve all had to challengeourselves to learn something new.
“It’s been a kick.”
