When I was a child, I was briefly instructed in the geological history of the Newport mesa in elementary school. Costa Mesa was once two places: a settlement called Harper, named after Gregory Harper, a grain farmer, and the town of Fairview, which was famed for its hot mineral baths. They failed after an earthquake stopped the flow of hot water. In 1920, when civic boosters decided to get serious about city building, they renamed the place Costa Mesa in recognition of its geological structure. The name means “tableland on the coast.”
That was about all I knew: that I lived on a tableland on the coast, about 100 feet above sea level. The history of Newport Bay, both its upper and lower parts, was not taught. Maybe this was because the natural history of the lower bay had been obliterated and the future of the upper bay was still being debated.
That changed after 1973, when I was in third grade. A twelve-year battle between conservationists Frank and Fran Robinson, the state, and the bay’s landlord, the Irvine Company, concluded. The Robinsons won. The bay’s waters, tidal marshes and uplands, were saved from becoming a monotonous urban landscape made of boat slips, rip-rap, yachts, and bay fill. The preservation of the Upper Newport Bay ensured that the bluffs and the bay that were created long ago, by forces mightier than even the most influential Newport Beach developer, stayed reasonably intact.
The mighty force that carved the river canyon and delta of the Upper Newport Bay may have been a river that doesn’t exist any longer, according to Ivan P. Colburn, Emeritus Professor of Geology, California State University, Los Angeles. He gave this “antecedent” river a name: the Newport River. In a talk he gave for the Society For Sedimentary Geology (SEPM), at their Western Regional Joint Meeting, in Long Beach in May 2003, and in a 2006 paper entitled “The Role of Antecedent Rivers in Shaping the Orange/Los Angeles Coastal Plain” Colburn says very plainly that he doesn’t think that the Santa Ana River made the Upper Newport Bay. Colburn theorized that the Newport River, fed by eleven tributary creeks and flowing west from a confluence formed by Peters Canyon, San Diego, and Sand Canyon creek, made the canyon that contains the Upper Newport Bay.
Colburn theorizes that the antecedent Newport River shoved its way through a changing landscape as tectonic forces lifted a ridge several hundred feet above the coastal plain. After passing this hurdle, the river made a capacious delta, which housed all the habitats of the current bay, including the friable marine terraces, the uplands, the tidal marshes, and the basin that the tides flow in, and out of.
(Today, the tidal process is often so unhurried that the footprints of raccoons and other foraging mammals are left undisturbed and can be seen inches under the water at low tide, clearly imprinted in the grey marsh mud.)
In Colburn’s telling of the making of the Orange and Los Angeles coastal plain, the Newport River was one of six “ephemeral” rivers that ran during the interglacial Sangamon age, 125,000 to 75,000 years ago. At that time, the climate hit the pause button between periods of glaciation. Water coursed down from the San Gabriel, San Bernardino and Santa Ana mountain ranges, and from the stumpy little hills scattered among the Los Angeles basin: Puente, Coyote, Repetto, Elysian and San Jose Hills. The six ancestral rivers dribbled and flowed down, and then snaked onto the basin that Los Angeles County sits on top of, creating a series of deltas much further inland and much higher. Sea level was about 100 feet higher than it is now.
These six rivers multi-tasked as they descended, carrying rock and sediment from the mountains and hills that got dumped whenever the flow of the rivers was checked, both taking from and giving to the earth, as all rivers do. This created the Los Angeles Basin where later extractive industries flourished, like the petroleum and the film industries.
The Sangamon age gave way to the Wisconsinan age, 75,000–11,000 years ago, the last glacial period before the Holocene, the age we live in now. The transition between a very warm age to a very cold one, trapped the water in ice. The coastline accordingly withdrew. At about 17,000 years ago, the coast of Los Angeles County was about eight miles away from the Port of Long Beach.
Some water became more available. The Wisconsinan age was glaciopluvial, meaning that there was much more rain. Southern California had a climate that was “comparable to the Pacific Northwest,” according to Colburn, and may have received over 80 inches of rain annually. This turned the ephemeral creeks and streams into rivers, giving them more erosive power than they’d ever had.
The power these rivers had is still visible. Imagine that you’re standing on the west bluff of the Upper Newport Bay. Looking east, you see Saddleback, with its twin peaks. (If you’re lucky, the moon is full and the sky is clear.) Directly in front of you is Eastbluff. Looking down, you see roughly 100 feet of eroded cliff, with cactus digging itself into the loose soil. Put your eyes in the back of your head, and travel west on 23rd Street, past Irvine, Santa Ana, and Orange avenues, to Newport Boulevard. Now you’re crossing into Westside Costa Mesa, the former working class neighborhood with the city’s only grange hall, now classed up with high-density condos.
Travel down Victoria Street, still heading west, until you stand on the Victoria Street overpass. What is it over passing, exactly? Why, the west side of the Newport mesa. You have just traveled between two points in an ancient landscape, from the water gap carved by the Newport River to the water gap made by the Santa Ana River.
There is no natural might that goes unchecked. Even as the Wisconsinan rain was swelling the rivers and watering the coastal plain, the earth kept its hand in, too. The Newport-Inglewood Fault, which was responsible for breaking my grandmother’s china in the late eighties, was active during this late stage in the Pleistocene era. It ruptured, producing a ridge, the Newport-Inglewood Ridge, presenting a challenge to the rain-engorged rivers. Before this, when the climate was drier, their deltas were further inland and easier to reach. But the rising ridge, which ran from the Santa Monica Mountains to the San Joaquin Hills, posed a threat to the free movement of the water.
The rivers, Colburn says, had great power of their own. They could move the earth, if not the heavens, and “entrench” themselves inside their beds, and flow at rapid speeds, too. So they did. Five of the rivers—the Los Angeles, San Gabriel, Bolsa Chica, Santa Ana and Newport rivers—bum-rushed the upwarping ridge that threatened to trap them inside the Los Angeles Basin. They were able to match in speed and might the rising earth because of their velocity and scouring power. They lengthened and deepened their beds to bring themselves into equilibrium with the new location and level of the ocean. And this made all the difference.
The ridge was transected, leaving behind water gaps and mesas where the water did not surmount the ridge. This explains the Dominguez and Signal hills, which always looked sadly orphaned to me, as I flashed past them on the 405 freeway as a child. They are mesas that were formed during this period. So are the Bixby Knolls in Long Beach and Landing Hill in Seal Beach. Only the Los Cerritos River did not make it. It became a wetland, and ultimately suffered the indignity that many wetlands in the 20th century suffered at the hands of private landowners and commercial interests.
The Newport River did make it. Colburn estimates that its drainage basin was 260 square miles, and its length, 20 miles. But this power came with a trade off: the entrenchment that allowed the rivers to drop to new sea levels, and allowed for higher volumes of water in their beds, also demanded a new commitment from the rivers to stay put.
Rivers wander; watch a rivulet of water run down a window someday, and you’ll see in miniature the motion of a meandering river. Geologists other than Colburn have supposed that the Santa Ana River wiggled back and forth between its normal course, cutting not only the Santa Ana water gap between Costa Mesa and Huntington Beach, but the Newport water gap, too. This is the going theory and is, today, widely accepted. An oft-quoted study entitled “Marshlands at Newport Bay” published in 1958 by scientists R.E. Stevenson and K.O. Emery, was influential in shaping theories about how the Upper Newport Bay was formed; it’s cited in the city’s “Upper Newport Bay Ecosystem Restoration Feasibility Study, Environmental Impact Statement,” published in 2000, and appears in the footnotes of dozens of articles in scientific journals.
This is where Colburn departs from his peers. “The geologic reasoning needed to support these assertions was not included in the articles,” he states, going onto to assert that the antecedent rivers were straight-jacketed by their deeply incised beds, making this sort of riverbed-hopping impossible for them to do. Stevenson and Emery are not the only scientists to favor this theory; Colburn quotes two other papers that theorize that the Santa Ana River created not one, not two, but no less than four water gaps between Los Angeles and Orange counties. This is a lot of work for one river, no matter how much water is propelling it across a plain.
Colburn’s research is quoted mistakenly in the current version of the Wikipedia article for the Santa Ana River: his idea that the Santa Ana River didn’t create either the Newport water gap, or the Upper Newport Bay, is ignored in favor of retaining the Santa-Ana-River-did-it-all theory.
He doesn’t take issue with the role of the Santa Ana river in the making of the Newport sandbar/peninsula and its ephemeral mudflats, which became Linda, Lido, Bay, Balboa and Harbor islands. The lower bay is younger than its sister embayment. Colburn allows that the “anecdotal” reports of the Santa Ana River flooding in the 19th century and entering the head of the upper bay through the entrance created by the Newport River are probable. Since there was more water in the oceans after the glaciers melted, saltwater intruded at least 2 miles up the river channel, slowing the rivers, which caused them to drop sediment further inland from the coast, raising their beds.
If the rivers ran their courses at the time the ridge was rising, it follows (if I understand Colburn’s argument) that the depth of the bed and the volume of water had to be deep enough, full enough, and fast enough to beat the uprising earth at its own game. Leaving its bed and weaving laterally over the plain to make more than one gap was not possible, Colburn states. And that’s where he leaves things.
It’s hard to visualize the kind of titanic power Orange County’s creeks had when they joined forces. Today, the Upper Newport Bay has only one major source of fresh water, San Diego Creek. The rest of Orange County’s creeks are contained in culverts. This keeps them from knowing each other as they did back in the good old glaciopluvial days when their polyamorous nature—creeks and streams like to take many partners—created a river.
Colburn’s research on the antecedent rivers is hypothetical, and this paper, as far as I can tell, was unpublished and has not been peer-reviewed, although other papers have. His work as a sedimentary geologist has been rewarded–and lauded–by his peers, most notably in 2017, when he received the 2016 A.E. Fritsche Lifetime Achievement Award “for his accomplishments to California geology” from the Pacific Section of SEPM.
If you want to see a remnant of the awesome geological past of the Newport Mesa, go to the Upper Newport bay, and scramble down the eroded sides of the 23rd street creek, which comes out of a culvert at the foot of 23rd street where it hits Irvine Avenue. The creek delivers urban runoff from the surrounding streets to the bay. Sometime before 1952, that creek and what is now called Cherry Lake, which was once a 40-foot deep spring-fed ravine, supplied fresh water to the Upper Newport bay. Both are both artifacts of an old hydrological system that was spread along the northwest bluff between Santiago Drive and Santa Isabel Avenue. All of it is gone, replaced by modern modes of place-making, like landscaping and the wholesale containment of natural systems, which—should they roar to life, unexpectedly—may yet surprise us all with their ancestral, epochal determination to create.