We travel back to a time when short-faced bears and dire wolves roamed the place we now call home. It's the conclusion of our walk on Mount Diablo's TRAIL THROUGH TIME.

The series features naturalist Ken Lavin and is sponsored by the Mount Diablo Interpretive Association in partnership with Save Mount Diablo. Videography by Macha Rose. Animations by Tanya Atwater, UC Santa Barbara. Music by Phil Heywood. Produced by Joan Hamilton.

A red pebble in this sandstone tells geologists that Bay Area rivers were flowing backwards (from west to east) when the rock was formed. How can that be?

Learn the history of your homeland while walking along the TRAIL THROUGH TIME, a series of geology videos featuring naturalist Ken Lavin. Sponsored by the Mount Diablo Interpretive Association in partnership with Save Mount Diablo. Videography by Macha Rose. Animations by Tanya Atwater, UC Santa Barbara. Music by Phil Heywood. Produced by Joan Hamilton.

In this episode, we find that rocks that should have been deposited over a span of 35 million years are missing on Mount Diablo. Why?

Find out on the TRAIL THROUGH TIME, a series of geology videos featuring naturalist Ken Lavin. Sponsored by the Mount Diablo Interpretive Association in partnership with Save Mount Diablo. Videography by Macha Rose. Animations by Tanya Atwater, UC Santa Barbara. Music by Phil Heywood. Produced by Joan Hamilton.

On a walk through 190 million years of geologic history, we take a break to admire a tree: the colorful, clever madrone.

It's part of the TRAIL THROUGH TIME, a series of geology videos featuring naturalist Ken Lavin. Sponsored by the Mount Diablo Interpretive Association in partnership with Save Mount Diablo. Videography by Macha Rose. Animations by Tanya Atwater, UC Santa Barbara. Music by Phil Heywood. Produced by Joan Hamilton.

The secluded meadows of Round Valley Regional Preserve lie just a few miles south of Brentwood, California. In this hour-long audio tour, you'll learn about the grassland's colorful history and the rich habitat it provides for golden eagles, kit foxes, and red-legged frogs.

If you are safe from the fires and curious to learn about another force that has shaped the Bay Area landscape, take a virtual walk on the TRAIL THROUGH TIME. It's a series of geology videos featuring naturalist Ken Lavin. Sponsored by the Mount Diablo Interpretive Association in partnership with Save Mount Diablo. Videography by Macha Rose. Animations by Tanya Atwater, UC Santa Barbara. Music by Phil Heywood. Produced by Joan Hamilton.

SENTINEL ROCK Mount Diablo's Half Dome? Geologically, it's not as silly as it sounds.

Take a virtual walk on the TRAIL THROUGH TIME, a series of geology videos featuring naturalist Ken Lavin. Sponsored by the Mount Diablo Interpretive Association in partnership with Save Mount Diablo. Videography by Macha Rose. Animations by Tanya Atwater, UC Santa Barbara. Music by Phil Heywood. Produced by Joan Hamilton.

SNAIL STORIES Need proof that the Bay Area was once under water? Have a look at marine turritellas preserved in rocks on Mount Diablo.

It's episode 14 of the TRAIL THROUGH TIME, a series of geology videos featuring naturalist Ken Lavin. Sponsored by the Mount Diablo Interpretive Association in partnership with Save Mount Diablo. Videography by Macha Rose. Animations by Tanya Atwater, UC Santa Barbara. Music by Phil Heywood. Produced by Joan Hamilton.

SANDSTONE FROM THE SIERRA Mighty rivers washed granitic rock from the Sierra Nevada westward into deep basins. You can see the evidence in the caves and castles at Mount Diablo's Rock City.

The TRAIL THROUGH TIME series features naturalist Ken Lavin and is sponsored by the Mount Diablo Interpretive Association in partnership with Save Mount Diablo. Videography by Macha Rose. Animations by Tanya Atwater, UC Santa Barbara. Music by Phil Heywood. Produced by Joan Hamilton.

Leap to the TERTIARY on the TRAIL THROUGH TIME, a series of geology videos featuring naturalist Ken Lavin. Sponsored by the Mount Diablo Interpretive Association in partnership with Save Mount Diablo. Videography by Macha Rose. Animations by Tanya Atwater, UC Santa Barbara. Music by Phil Heywood. Produced by Joan Hamilton.