Calaveras Dam - The Real 'Shark Tank'

Crews constructing the SFPUC’s new Calaveras Dam in the East Bay uncovered a geologic layer that happened to contain thousands of fossils. Through a cooperative agreement with the University of California Museum of Paleontology (UCMP; Berkeley, CA), those fossils are now being cleaned, analyzed, and catalogued.

“We transferred all of the fossil specimens to UCMP this year,” said JT Mates-Muchin, the SFPUC’s Environmental Compliance Manager who helped broker the agreement. “Fossils are a non-renewable resource. It is important that they are carefully catalogued and preserved for scientific research.”  

 A Megalodon Shark Tooth Being Scanned in the Lab.

The lead researcher and lab manager at UCMP, Cristina Robins, and her team are beginning to tease information out of the fossils.   Fifteen million years ago, the site of Calaveras Reservoir was located at the mouth of a vast inland sea that stretched into the Central Valley.  Just like in the seas of today, there was a lot of plant and animal life throughout. When they died, they left a fossil record.

This included sharks, lots of sharks. More than 2,000 shark teeth have been found from 35 species. These include many from requiem and mako sharks. Some teeth from the 35-foot megalodon shark have turned up as well. What do these shark teeth tell us?

1. The area around Calaveras Dam was once completely submerged by water.
2. The depth of the ocean could have been as deep as 700 to 1,000 meters.
3. The distribution of species is similar to fossil locations as far as way at Gatun, Panama.
4. Calaveras has a higher diversity of sharks than other sites.

At this point the paleontologists have only begun to scratch the surface of the Calaveras fossils, no pun intended.

The teeth from 35 different species of shark have been found at the Calaveras Dam Replacement Project.

We look forward to learning more secrets about the Bay Area’s past through these amazing fossils.

Keep up to date on the Calaveras fossils through the UCMPFacebook Page.

A 30 foot long predator left its tooth at Calaveras Dam. The Megaladon tooth is being analyzed at UCMP.

 See you around the Valley!

Fossils from the Calaveras Dam Replacement Project Find their New Home

The San Francisco Public Utilities Commission (SFPUC) has been working since 2011 to build a replacement Calaveras Dam out of seismic concerns for the existing 93-year-old dam in the Sunol Valley.

To make space for the new earth and rock-fill dam, the Calaveras Dam Replacement Project has had to move almost 10 million cubic yards of soil and rock. While moving all this earth, the project team began to find what has been called one of the greatest fossil finds in the Bay Area in decades.

To date more than 1,300 specimens have been discovered. Most them are fossils from an ancient ocean and beach area approximately 15 to 20 million years ago. Water covered much of California back then, and an inland ocean extended to the Central Valley.

Many of the fossils are high-quality specimens that can be used to further research into evolution or global change. (UC Berkeley photos by Sara Yogi)

Amongst the vertebrate fossils are marine mammals, like baleen whales or Mysticetes and toothed whales and dolphins or Odontocete; and Desmostylus, an herbivorous hippo-like marine mammal), seals or sea lions, sharks, and bony fish, such as halibut.  The invertebrates include scallops (some as big as a dinner plates), clams, snails, cockles, mussels, crabs, and barnacles. The team believes it has found a new species of whale among the dozens of whale skulls found.

Researchers have pieced together the jawbone from a 15- to 20 million-year-old whale. 

(UC Berkeley photos by Sara Yogi)

Researchers can tell this area was near to shore because they have also found plant material that washed into the ocean from land, including pine cones, palm trees, leaves, and wood. They can tell that the Bay Area was warmer back in this time, and the ocean teemed with life.

Through an agreement between SFPUC and the University of California Museum of Paleontology (UCMP) the entire collection of fossils will now be housed within the UCMP collections. The fossils represent California’s fossil heritage and as such, belong to all the citizens of California, and will be managed on their behalf by the University of California Museum of Paleontology. 

The UCMP assembled a team to manage this collection, including a Lab Manager – Dr. Cristina Robins, many undergraduate students, two graduate students per semester, and volunteers.

Graduate student Mackenzie Kirchner-Smith uses a brush to spread adhesive over a fossil found during the Calaveras Damn replacement project. (UC Berkeley photos by Sara Yogi)

Dr. Robins and her team painstakingly chip away the rock from the fossilized bone to identify each specimen. It is laborious work. They often find new specimens inside the rock blocks around other specimens. More fascinating fossil discoveries lay ahead for the UCMP team.

Fossils waiting to be released from rock fill the small lab located at UCMP.

And we at the SFPUC know the fossils are in excellent hands.

See the video and read more here:

See you around the Valley!

What is a desmostylus and what is it doing in the Sunol Valley?

Photo courtesy of www.alchetron.com

A Desmostylus was a hippo-like creature that lived about 20 million years ago. It happens to be the only order of marine mammal to have gone extinct. Some individuals lived along the shoreline of an ancient ocean that used to be located where the Sunol Valley is today.

If you stumbled upon this would you know it was a rib cage?  What it looked like prior to Excavation

During excavation of the Calaveras Dam Replacement Project, the project paleontologists found not only a few teeth belonging to these strange creatures, but recently found an entire rib cage. Removing the fossilized rib cage of an animal that likely weighed between 200 and 400 pounds in life is no small task.

First the bone had to be cleaned and separated as much as possible from the surrounding rock on the hillside.

Above is the picture after our fossil was cleaned and ready to be removed.

In order to physically remove it from the hillside, crews used a lift to grab the entire rib cage. Now that the rib cage has been safely removed from the construction site, it awaits further stabilization treatment by project paleontologists. 

See you around the Valley!

What do water pipes, water conservation, fossils and dams have in common?

They were all part of the cool topics shared with the Sunol Glen School students last week at their annual Earth/Science Day festivities.  We at the San Francisco Public Utilities Commission were honored to be a guest again this year to share information about the Hetch Hetchy Regional Water System.

We are always surprised and amazed at the enthusiasm and smarts of these first through eighth graders. Did you know that the California State Flower is the Golden Poppy? They did. Did you know that you could save your shower water in a bucket and water your plants with it? They did. Did you know the Sunol Valley was once a coastline? Many of them knew that, too. They enjoyed looking at the 20 million year old fossils unearthed during the construction of the Calaveras Dam Replacement Project, including a prehistoric shark tooth, seashells and rocks from the site.

We had a blast at Sunol Glen School and can’t wait to be back!

Now, for bonus points, what is the California State Fish? (Sunol Glen students, no telling!)

Calaveras Dam in the News

Just last week, we were able to share our story about recent fossil finds here at the Calaveras Dam Replacement Project.  As our crews are busy working on major spillway work and grouting operations for the new replacement dam, we were able to take a moment to highlight the interesting fossil finds out here.

Check out the story here from the San Jose Mercury News: Fossils Found at Calaveras Dam

The Calaveras Dam Replacement Project is the largest project of the Water System Improvement Program (WSIP) to repair, replace and seismically upgrade key components of the Hetch Hetchy Regional Water System.

For more information, please contact us at mle@sfwater.org

Sunol Glen School Students Celebrate Earth Week with Us!

What do ancient shark teeth, wasps nests, and owl pellets have in common? All were on display last week at the Sunol Glen School’s Earth Day Science celebration last week.  We were lucky enough to have been invited to participate, along with other local groups and leaders.  The kids, grades Kindergarten through eighth grade, learned about the importance of building a seismically upgraded replacement dam at the Calaveras Reservoir. Our project Geologist Bradley Erskine showed some fascinating fossils found at the Calaveras site during construction. The biggest hit with the students by far was a prehistoric shark tooth possibly from a Megladon, dating at approximately 20 million years old.  We had a great time answering questions about how water gets to your tap and the importance of the Water System Improvement Program to future generations.

Having met the leaders of tomorrow at Sunol Glen School, we know the future is in good hands! Sunol Glen Schools students proved themselves to be inquisitive and curious scientists at Earth Day on May 2^nd. 

Geologist Bradley Erskine and Natural Resources staffer Amy Dawson share fossil finds from Calaveras Dam to the Sunol Glen School students

Sample fossils of prehistoric shark teeth dating over 20 million years old

Whales in the Sunol Valley?

Since construction began at the Calaveras Dam, team paleontologists have had some remarkable finds from ancient shark teeth to marine mammal vertebrae all collected during the excavation of over 4 million cubic yards of earth over the sediments that were once an ancient sea floor.  

Just this week, project paleontologists found a portion of an ancient whale skull in the slope above the spillway excavation of the new dam. The skull is almost a yard long and relatively intact, except for a small portion of the right rear section which is missing. Our paleontologists are still researching the find but initially assess the fossil to belong to a Mysticete (or baleen) whale, from the family of Humpback, Grey or Blue whales that live in the oceans today and forage on plankton. This fossil was discovered in the temblor sandstone formation which makes it over 20 million years old.

The project takes important steps to salvage these paleontological finds for educational purposes. The critical construction work to build a replacement dam has not been affected and continues, while we discover amazing fossils to add to the rich history of this valley.

Paleontologists Bruce Hanson and Jim Walker work on uncovering fossils at Calaveras Dam. Photo credit: Robin Scheswohl

In November 2013, a collection of bones including vertebra from a marine mammal were discovered on the lower portion of the Spillway.  It appears to show a complete cross section of the body, neural arch and measures 15 x 7 centimeters. Some of the other bones appear to be ribs. None of the specimens found interfered with construction activities and the specimen still remains in the rock.

Fascinating Fossil Finds at Calaveras Dam

Every day, our scrapers dig soils and earthen materials to make room to build the replacement Calaveras Dam.  We have special staff who monitor high sensitivity areas during construction searching for paleontological and cultural resources, which are protected by federal and state laws.  Construction crews also attend environmental training about the identification and protection of paleontological and cultural resources. Calaveras Dam project teams have discovered fascinating finds within our construction site. 

What are Paleontological Resources?

Paleontological resources include: remains of prehistoric/extinct plants and animals, petrified wood, fossil leaves, fossil remains of vertebrate and invertebrate organisms, fossil tracks and track ways, and plant fossils, typically of Pleistocene Epoch (> 12,000 years ago) or greater age. 

What have we found?

Fossilized plants such as wood, leaves, and a pine cone have been salvaged from the site.  Invertebrates uncovered include: scallops, clams, snails, barnacles and worms.  We have also found shark teeth that are still being analyzed but may be related to a great white shark although much larger (Think “Jaws” and then some).

Our most fascinating finds are linked to prehistoric marine mammal(s).  This includes an intact portion of a backbone of a whale.  These finds are still being analyzed by experts.

Why?

Most of the fossils have been found in the 20 million year old marine sandstone called the Temblor Formation.  The Sunol Valley area was below sea level in the Pacific Ocean about 20 million years ago and has since been uplifted along with the rest of the Coast Ranges. Life along the old coast was similar to today, with abundant clams, mussels, sea worms and other invertebrate organisms living in the sand. But the fossils also document significant differences from today’s relatives and provide important information about the details of evolution and environments of the plants and animals represented by the fossils.  We continue to work to preserve and protect these neat findings every day.

Fossils & Shark Teeth discovered at the Calaveras Dam Replacement Project Site

Seashells and Secant Piles

A recent trip to the Sunol Valley by SFPUC photographer Katherine DuTiel produced a photo that, by striking coincidence, looks remarkably like one taken on the Bay Division Pipeline Project on the Peninsula.

Look closely to see which is which!





Shown here is the receiving shaft of the Bay Division Pipeline micro tunnel section on the Peninsula. The project was forced to tunnel under a culturally and environmentally sensitive area at the end of this 9 mile pipeline. The secant wall in the shaft consists of a series of drilled piers filled with concrete. They are arranged concentrically to provide a continuous concrete wall that supports the shaft.



The Sunol Valley area was covered by the Pacific Ocean about 20 million years ago. Life along the old coast was similar to today, with abundant clams, mussels, sea worms and other invertebrate organisms living in the sand. The sandstone formation that represents the old ocean deposits is called the Temblor sandstone, and contains fossils from this old coastline. The photograph shown above is a fossil scallop collected by geologists at the Calaveras Dam Replacement Project.