​​​​Snow Productions BI 

Bainbridge Island Geology: Video Previews, Field Trips

Discover how a small island in Puget Sound can reveal the larger picture.

Synopsis
 
A geologist finds clues to big events on a small island.  Evidence in the rocks reveals underwater landslides, volcanism, faults and earthquakes that continue to shape the landscape.
  
Part One 
The Blakeley Formation 
and the Blakely Harbor Formation​
The story begins on Bainbridge Island, a small island west of Seattle.  Geologist Gregory Geehan leads us into the deep past to find the oldest rocks on the island.  They began as sediment, under the sea.  Once buried thousands of feet, we now find them raised to the surface, bent, tilted deformed.  They provide evidence of uplift on the Seattle Fault. 




Part Two
Earthquakes and Faults
Next we look for clues in the surrounding region for the cause of such upheaval.  Tremendous seismic activity comes to light on the nearby Pacific Coast.  The seafloor has been pushed up into the Olympic Mountains.  Areas of salt-killed trees from Canada to California reveal a magnitude 9 subduction zone earthquake 300 years ago.  Tectonic movement on the San Andreas Fault in California adds a further twist to the forces that have tilted thousands of feet of rock in the Seattle area… and have given Bainbridge Island an irregular shape.

Part Three
Our Glacial Heritage
​The last glacier advances into our region about 17,000 years ago and transforms the landscape. ​​
What will these layers tell us about past events?