Featured Research

from universities, journals, and other organizations

Evidence of ancient lake in California's Eel River emerges

Date:
November 14, 2011
Source:
University of Oregon
Summary:
A catastrophic landslide 22,500 years ago dammed the upper reaches of northern California's Eel River, forming a 30-mile-long lake, which has since disappeared, and leaving a living legacy found today in the genes of the region's steelhead trout, scientists report.

View down the Eel River, with the reconstructed ancient lake surface in blue.
Credit: Ben Mackey, Caltech

A catastrophic landslide 22,500 years ago dammed the upper reaches of northern California's Eel River, forming a 30-mile-long lake, which has since disappeared, and leaving a living legacy found today in the genes of the region's steelhead trout, report scientists at two West Coast universities.

Using remote-sensing technology known as airborne Light Detection and Ranging (LiDAR) and hand-held global-positioning-systems (GPS) units, a three-member research team found evidence for a late Pleistocene, landslide-dammed lake along the river, about 60 miles southeast of Eureka.

The river today is 200 miles long, carved into the ground from high in the California Coast Ranges to its mouth in the Pacific Ocean in Humboldt County.

The evidence for the ancient landslide, which, scientists say, blocked the river with a 400-foot wall of loose rock and debris, is detailed this week in a paper appearing online ahead of print in the Proceedings of the National Academy of Sciences.

The National Science Foundation-funded study provides a rare glimpse into the geological history of this rapidly evolving mountainous region.

It helps to explain emerging evidence from other studies that show a dramatic decrease in the amount of sediment deposited from the river in the ocean just off shore at about the same time period, says lead author Benjamin H. Mackey, who began the research while pursuing a doctorate earned in 2009 from the University of Oregon. He is now a postdoctoral researcher at the California Institute of Technology.

"Perhaps of most interest, the presence of this landslide dam also provides an explanation for the results of previous research on the genetics of steelhead trout in the Eel River," Mackey said, referring to a 1999 study by U.S. Forest Service researchers J.L. Nielson and M.C. Fountain. In their study, published in the journal Ecology of Freshwater Fish, they found a striking relationship in two types of ocean-going steelhead in the river -- a genetic similarity not seen among summer-run and winter-run steelhead in other nearby rivers.

An interbreeding of the two fish, in a process known as genetic introgression, may have occurred among the fish brought together while the river was dammed, Mackey said. "The dam likely would have been impassable to the fish migrating upstream, meaning both ecotypes would have been forced to spawn and inadvertently breed downstream of the dam. This period of gene flow between the two types of steelhead can explain the genetic similarity observed today."

Once the dam burst, the fish would have reoccupied their preferred spawning grounds and resumed different genetic trajectories, he added.

"The damming of the river was a dramatic, punctuated affair that greatly altered the landscape," said co-author Joshua J. Roering, a professor of geological sciences at the University of Oregon. "Although current physical evidence for the landslide dam and paleo-lake is subtle, its effects are recorded in the Pacific Ocean and persist in the genetic make-up of today's Eel River steelhead. It's rare for scientists to be able to connect the dots between such diverse and widely-felt phenomena."

The lake's surface formed by the landslide, researchers theorize, covered about 12 square miles. After the damn was breached, the flow of water would have generated one of North America's largest landslide-dam outburst floods. Landslide activity and erosion have erased much of the evidence for the now-gone lake. Without the acquisition of LiDAR mapping, the lake's existence may have never been discovered, researchers say.

The area affected by the landslide-caused dam accounts for about 58 percent of the modern Eel River watershed. Based on today's general erosion rates, researchers theorize the lake could have been filled in with sediment within about 600 years.

"The presence of a dam of this size was highly unexpected in the Eel River environment given the abundance of easily eroded sandstone and mudstone, which are generally not considered strong enough to form long-lived dams," Mackey said.

He and his colleagues were drawn to the Eel River -- among the most-studied erosion systems in the world -- to study large, slow-moving landslides. "While analyzing the elevation of terraces along the river, we discovered they clustered at a common elevation rather than decrease in elevation downstream, paralleling the river profile, as would be expected for river terraces. This was the first sign of something unusual, and it clued us into the possibility of an ancient lake."

The third co-author on the paper was Michael P. Lamb, professor of geological and planetary sciences at the California Institute of Technology in Pasadena, Calif.

The National Center for Airborne Laser Mapping provided LiDAR data used in the project. Additional funding support came from the Keck Institute for Space Studies.


Story Source:

The above story is based on materials provided by University of Oregon. Note: Materials may be edited for content and length.


Journal Reference:

  1. Benjamin H. Mackey, Joshua J. Roering, Michael P. Lamb. Landslide-dammed paleolake perturbs marine sedimentation and drives genetic change in anadromous fish. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1110445108

Cite This Page:

University of Oregon. "Evidence of ancient lake in California's Eel River emerges." ScienceDaily. ScienceDaily, 14 November 2011. <www.sciencedaily.com/releases/2011/11/111114152404.htm>.
University of Oregon. (2011, November 14). Evidence of ancient lake in California's Eel River emerges. ScienceDaily. Retrieved August 29, 2014 from www.sciencedaily.com/releases/2011/11/111114152404.htm
University of Oregon. "Evidence of ancient lake in California's Eel River emerges." ScienceDaily. www.sciencedaily.com/releases/2011/11/111114152404.htm (accessed August 29, 2014).

Share This




More Plants & Animals News

Friday, August 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com
Raw: Australian Sheep Gets Long Overdue Haircut

Raw: Australian Sheep Gets Long Overdue Haircut

AP (Aug. 28, 2014) Hoping to break the record for world's wooliest, Shaun the sheep came up 10 pounds shy with his fleece weighing over 50 pounds after being shorn for the first time in years. (Aug. 28) Video provided by AP
Powered by NewsLook.com
Minds Blown: Scientists Develop Fish That Walk On Land

Minds Blown: Scientists Develop Fish That Walk On Land

Newsy (Aug. 28, 2014) Canadian scientists looking into the very first land animals took a fish out of water and forced it to walk. Video provided by Newsy
Powered by NewsLook.com
Huge Ancient Wine Cellar Found In Israel

Huge Ancient Wine Cellar Found In Israel

Newsy (Aug. 28, 2014) An international team uncovered a large ancient wine celler that likely belonged to a Cannonite ruler. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins