Shape Shifters: Debris Basins and the San Gabriels
01.27.2011, 4:54 pm
Filed under: Uncategorized

a mouth to the mountain, debris basin at the top of Pine Cone Road

“We survived… we survived.” These were the calmly spoken, unsolicited words of a man who noticed us peering over the fence and taking photos of the sweeping installation of infrastructure just outside his garage door. He went on to explain that he had been living at the top of Pine Cone road in La Crescenta-Montrose, CA for many years, and admitted that there had been some big flooding, mudslides and fires. He had been evacuated during some of the worst.  And he had heard tell of boulders the size of cars pounding down his suburban street. He said that the heat of the fires had been the most incredible. But he “felt safer now,” especially with this debris basin above his house. He had learned a lot over the years. “If the canyon weren’t so steep,” he said, he’d climb up and plant more trees in attempt to stabilize the vertical rise of crumbling earth that looms behind his home. He paused, then exclaimed how incredible the air is up here away from the city.  It was true, the air was fresh and the view was dramatic. From the 41% grade of Pine Cone Road we could see Los Angeles spread far and wide across the valley below.  But we couldn’t hear it.  And we couldn’t sense the pressure of its presence.

In 2010, dramatic flooding in the San Gabriels resulted from February rains. Despite a record setting 18 inch rainfall in a single week this past December, no major damage occurred.  The Pine Cone Road resident said he had been very nervous that week.  He was up late at night anticipating the worst.  But the debris never came.  As we left, we noticed a few dozen sand bags piled against the nearly vertical hillside that towered above his garage and we wished him luck.

midway down Pine Cone Road concrete barriers aren’t for controlling traffic and people–they’re for deflecting runaway debris

We were intrigued with the San Gabriel debris basins even before arriving in Los Angeles and without ever having seen one in person. Reading John McPhee had set the stage years ago for us, and the glimpses offered in Google Earth were visually stunning. Aerial views provide a sense of scale and a degree of access impossible from the ground view.  We could see the variety of minimalist forms that the basins take; sense their sheer numbers, scattered along the base of the mountains; and shudder at the stark proximity of these “bowls” and “shoots” in relation to endless and vulnerable cul-de-sacs and backyards.  Nevertheless, it’s only on the ground and up close that we got a true sense of the material threat the disintegrating San Gabriel Mountains pose to residential life in Los Angeles.

survey of debris basins visited by FOP, Google Earth

The San Gabriels are among the fastest growing and steepest mountain ranges in the world. Their upward thrust is continuous.  As a result, they are located within concentration of criss-crossed fractures and faults.  They’re also falling apart, as in coming “down,” incredibly fast.  The San Gabriels bedrock has been broken and shattered by earthquakes and undercutting of streams.  These mountains are infamous for being avoided by rock climbers because of their unsuitable climbing material.

We had come to Los Angeles as participants in Geoff Manaugh’s recent studio intensive, the Landscape Futures Super-Workshop. It was Geoff’s invitation that established a context for us to visit several of the debris basins and start to imagine what we might make of them in our work. During our week in L.A. we visited six of the 162 basins managed by the Los Angeles County Department of Public Works.

Blanchard debris basin (note sign, “this drains to the ocean”).

Dunsmuir debris basin

Haines debris basin

the enormous Cucamonga Creek debris basin in Rancho Cucamonga, CA

the elegant slope of Cooks basin

Cooks basin’s channel to the ocean

For FOP, each debris basin exists as a “signaling device.” Each announces that geologic change unfolds here, right here, in continuous and unpredictable ways.  Each basin also exemplifies the best human attempt to build, plan for and contain the potentially uncontainable: the material reality of geologic time and force. When flowing debris activates these basins, an incredible shape-shifting occurs: the force and materiality of geologic time actually become perceivable. Solid becomes liquid, the far becomes near, virtual becomes actual, top becomes bottom, and a precarious equilibrium looses its poise as the habitable instantly becomes uninhabitable.

the edge of Haines debris basin

Our time with the debris basins reminded us of Aaron Betsky’s thoughts on Instability, from the collection, Landscape + 100 words to inhabit it:

“Despite the fact that we experience it as immutable, the land we inhabit is inherently unstable.  It is the very ability of the land to change both instantly. . . and its gradual transformations. . . that creates the differential–the change in elevations, material and direction–producing the riches we mine . . . .”

The material fact and forms of the debris basins make visible the instabilities at play in mountain building and erosion. They also make visible what it means to be a human living in intimate proximity to a mountain range that has the tendency to spontaneously become a flow. We think humans can learn much from the proximity of this material instability.  Debris basins pinpoint especially precarious intersections of architecture, infrastructure, technology and the geologic.  They lay bare the human vulnerabilities that exist here. What can we design to meet such junctures when we recognize that the mountains are simply doing what they have done for the past 20 million years–risen, crumbled, and washed their way towards the sea?

The development of Los Angeles as a major urban center, in the time between this rising and tumbling, triggers all kinds of questions (aesthetic, philosophical, economic, social and political) that are only becoming increasingly more relevant to cities around the world.  In areas highly prone to earthquakes, floods, fires and landslides, the question of urban and suburban development isn’t simply a question of whether it’s “good” or “bad.”  It’s a question of how to realize the full magnitude of what it means to design and engineer in relation to geologic force itself–a constant circumstance of life on our planet.

What does it mean to let geologic materiality move, unabated, at its own speed and velocity? Conversely, how much might we comprehend what it takes to re-direct geologic flows? What does it mean to have temporary holding zones, such as these basins, where geologic materiality gets remixed and then relocated? In what ways are we capable of knowing geologic “accumulation”?

We think it’s worth looking more closely at these L.A. debris basins.  We intend to pay some close attention to how they attempt to meet the forces they are designed to confront. Though they aren’t designed to last 1,000,000, 100,000, or even 10,000 years, these basin will theoretically need to exist and be maintained continuously for as long as the San Gabriels head towards the sea with Los Angeles in their path.

The basins, and other such designs, appear even more vital in light of a recent report declaring that most of California will eventually experience catastrophic flooding and violent storms for which the state is wholly unprepared. The apparently inevitable event has the nickname: the ARk storm. The next time it occurs, Los Angeles will undergo an immediate reconfiguration of itself as city.

While standing at the edge of Haines basin, we posed questions to the site manager for the Army Corps of Engineers. He was facilitating the emptying of the basin (something that must be done regularly). What caught our attention, and everyone else’s in our group, was his offhand comment about what he called the “geologic problem” in the surrounding hills. When prompted, he went on to say he felt the area was “locked and loaded.”  He had been watching this area crack and deteriorate over time, and the entire bowl of surrounding mountain might give way even without a rainstorm.  He said he and the workers kept their eyes on the surrounding hills constantly.

In response to our first encounter with the San Gabriel debris basins, we’ve decided to embark on a long-term project to map their locations and create a typology of their forms.  These basins clearly fall into our ongoing research category of humans’ “best attempts” to design in relation to geologic materiality, force and time. Stay tuned for updates on the project in the coming months.


It’s also worth mentioning that during the Landscape Futures studio, we spent the week with a stellar group of people – all working to respond in some way to landscape future scenarios. Our colleagues for the week included teachers and students from The Bartlett (London)Columbia University and the Arid Lands Institute. Our host for the studio, The Center for Land Use Interpretation, completed a fantastic exhibition about the L.A. debris basins in 2006, which you can explore online at the following link: Dissipation and Disintegration: Antennas and Debris Basins in the San Gabriel Mountains. Also stay tuned for Geoff Manaugh’s Landscape Futures exhibition at the Nevada Museum of Art, opening this summer, featuring work from studio participants.

In between presentations, thanks to Geoff’s curated site list, we experienced many new sites around the edges of Los Angeles. Our roving field studies included the L.A. River Headwaters, the Cascades (a.k.a. Los Angeles Aqueduct Terminus), and Hansen Dam – additional examples of human designed infrastructures built to control, channel and protect and protect from the geologic resources of Los Angeles.

L.A. River headwaters

Hansen Dam

The Cascades


[…] Shape Shifters: Debris Basins and the San Gabriels « Friends of the Pleistocene […]

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This was a pleasure to read. I’m one to scour google maps for interesting infrastructure in the Los Angeles Basin that attempt to deal with the unrelenting forces of nature: mountains, floods, fires, etc.

Comment by Carter R

oh my! This blog is catnip for me. Been an infrastructure freak all my life.

Debris basins are special favorite of mine since I read about them in John McPhee’s book. “The Control of Nature” I think it was.

Comment by zhando

[…] defenses against its eroding mountain backdrop, see the Friends of the Pleistocene’s much more extensive tour of the region’s debris basins. And if you are in L.A. and have the time and energy, you may wish to walk (or bike) the 10.6-mile […]

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