Geology of the Cascadia Subduction Zone: A Weekend Field Course

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Friday, June 12th, 2015

Most of us living on the West Coast have heard talk of the Cascadia Subduction Zone, and the giant megathrust earthquake and tsunami that we are expecting. But did you know that this active tectonic plate margin also influences everything from the shape of British Columbia’s famously rugged landscape, to the formation of mineral deposits such as at the proposed Catface Mine?

This three-day field course will introduce you to our subduction zone, with visits to outcrops in and around Tofino, which illustrate how, when, and why our Earth moves.

Topics to be covered:
- What is a subduction zone?
- How do scientists know about past earthquakes and tsunamis here?
- Why does sea level go up and down?
- Why are our mountains and valleys where they are?
- What are the main rock types around Tofino and Ucluelet? (breaking the basalt myth!)
- How did the copper on Catface Mountain get there?

Friday, June 12
Evening Classroom: 7:30-9pm (Meet at Raincoast Education Society office in basement of Ecolodge)
Introduction to the Cascadia Subduction Zone, and what it means for those of us who live on the West Coast

Saturday, June 13
Morning classroom: 8am-9:30am
Introduction to sedimentary rocks, turbidite deposits, and tectonic structures

Field: 10am-5pm
Full day in the field, looking at turbidite deposits, learning how to tell sedimentary rocks from basalt, identifying folded beds and faults in the field, and looking at evidence for sea level change on Chestermans Beach. Also a visit to a glaciated outcrop and discussion of how erosion works.

Evening classroom: 7:30pm-9pm
Introduction to igneous rocks and how and why mineral deposits such as Catface form

Sunday, June 14
Field: 8am-1pm
Half-day in the field, looking at igneous rocks including Tofino’s one tiny outcrop of real basalt, and a granite and its contact relationships with the surrounding sedimentary rock, and even some metal deposits associated with that granite. Also, examples of how geology influences erosion and therefore our geography, as well as field evidence of ground shaking from our last big earthquake.

Course finishes at 1pm.

Recommended Equipment:
Please wear sturdy footwear as we will be walking over slippery rocks at low tide. Please dress appropriately for the weather, as the course is almost enitrely outdoors.

Items you might want to bring along include:
- hand lens or magnifying glass
- camera
- notebook and pencil

You are welcome to bring a geological hammer, too - but if you do, please also bring safety glasses and use them!

About the instructor:

Dr. Jacqueline Windh is a geologist, photographer, and writer. She received her PhD in 1992 from the University of Western Australia. The focus of her doctoral research was structural geology: the study of movements within the Earth’s crust, and particularly how faults and fractures influence where gold and other metals are deposited. She applied this knowledge working as a geological consultant to the minerals industry for nine years, in Australia, Chile, Peru, Argentina, and Canada.

Register at:
http://raincoasteducation.org/register