Please upload a photo of yourself and your GPS, or if you prefer, just a photo of your GPS, taken with either the Pioneer Church or the Baker Cabin in the background. If your camera is also your GPS, use some other object i.e. name tag, a personal item, a piece of paper with the your name on it, etc. The important thing is that the picture demonstrates you are a cacher logging the Earthcache, not an armchair tourist.
The Carver Gap is near the independent, unincorporated community of Carver, Oregon, on the Clackamas River. Before the Missoula Ice Age Floods of 13,000 to 15,000 years ago the Clackamas River was impounded by a volcanic ridge.
The ridge consisted of two or more of the "Boring Volcanoes" close enough together to actually form a dam across the mouth of the valley. Formed of andesitic lava similar to the Cascade volcanoes, these volcanoes pushed up through the layers of basalt from the Columbia River Basalt (CRB) flows. As the volcanoes pushed upward they apparently melted some of the CRB and incorporated it into the lava making it "Andesitic-Basalt" or "Basaltic Andesite".
Basaltic andesite is a volcanic rock containing about 55% silica. It is distinct from basalt and andesite in having a different percentage of silica content. Minerals in basaltic andesite include olivine,, augite and plagioclase.
This unique lava can be easily identified by the flow-banding. These are parallel lines in the lava formed as it flowed and folded over itself. Columbia River Basalt is too thin and Andesite is too thick to fold in this manner. Boring lava is great building material because it is an ideal stone for cutting into building blocks due to its tendency to break along the flow banding parallel lines.
The Clackamas River filled the Clackamas Valley eventually cutting through the volcanic ridge that impounded it. As the water drained from the Clackamas Valley, it enlarged the gap between two of the Volcanoes and created a waterfall about 50 feet above where the Clackamas River is today.
During this waterfall rocks were caught in little whirlpools and cut potholes in the bedrock. Potholes are formed when a rock starts spinning in the water flow and drills or cuts small holes in the bedrock below. This action can make a hole several inches or feet deep. If the water level changes, as it did with the Clackamas River, these potholes are left stranded on dry bare rock. These holes were sometimes used by native peoples for grinding.
(1) List the name “GC8J5BZ Carver Gap Earthcache” in the first line of your email/message.
(2) Query: There are several of these potholes in the bedrock at this location on the south side of the Clackamas River across from Carver, Count the number of holes in the rocks in front of the Pioneer Church. Count the number of holes in the rocks northwest of the Baker Cabin. How many holes can you find? How deep are each of the holes?
(3) Describe the texture and color of the rocks with the holes.
(4) Query: A rock formation located west of the Baker Cabin was quarried by Horace Baker in the late 1800s. These rocks are very high grade and 3 to 8 million years old. Are the Quarry rocks Columbia River Basalt or Andesitic-Basalt?
Tons of rock was quarried and loaded into barges in the area which is now the Carver Boat Ramp. During the spring floods the barges were floated down the Clackamas River to Oregon City and distributed from there.
When the Missoula Ice Age floodwaters burst out of the Columbia River Gorge it filled the Portland Basin with slurry of water, rocks, trees, animals including mastodons, etc. Much of the floodwaters flowed west around the Boring Volcanoes but the Rock Creek Channel cut through them. This channel, as well as the floodwaters from around the west, pushed a load of gravel in front of the waterfall at Carver Gap and actually dammed the Clackamas River for a brief time. The 400 foot deep floodwaters from the Portland Basin flooded over the top of the dam, filling the Clackamas Valley to where Estacada is today. It brought silt from Washington State to become the valley's soil.
Water coming down from the Cascade Mountains brought sediment with it which added to the soils backing up behind the temporary Carver Gap dam. Then, at the end of the Missoula Ice Age Floods, the Clackamas River eventually cut its way through the gravel, leaving the scars that we see today as it twisted and turned to find its way out of the valley. The Clackamas River never returned to its former bed near where the Clackamas Expressway is today. Instead, it was forced to make an abrupt left turn where it hugs the mountain and twists its way though Gladstone to finally meet the Willamette River.
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Written permission from Rick Thompson to use his material in Earthcaches.
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1/22/19
Dear Maureen;
I was pleased to have met with you to learn more about EarthCaches and the opportunity it presents to expand knowledge about the history of and at the Baker Cabin site.
To this end, our Society has approved your request to site your informational Earthcache .
If possible can you include some information for the visitors use?
Such as; “Site is open daylight hours for self-guided tours of interpretive panels at points of interest. Event rentals and in-person tours, including buildings, can be arranged by contacting the Society.
We are volunteer run and appreciate our visitor’s good manners, particularly with dogs and cleanup of any trash.”:
Once your cache is published, please contact me with links so that we might enjoy, view and share.
Best regards, Chris Guntermann, President, Baker Cabin Historical Society
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Missoula Ice Age Floods Bibliography/Reading List
Lake Missoula Flood Channels, Obstacles and Overlooks in the Portland/Vancouver Area by Thompson, Rick 2008
Fire, Faults & Floods: A Road & Trail Guide Exploring the Origins of the Columbia River by Mueller/Mueller 2005
Cataclysms on the Columbia: The Great Missoula Floods (recent edition) by John Eliot Allen, Marjorie Burns, Scott Burns. One of the best books on the subject. 1986/2009 Second Edition
Bretz's Flood: The Remarkable Story of a Rebel Geologist by John Soennichsen 2008/2009
On the Trail of the Ice Age Floods A geological field guide to the Mid-Columbia Basin by Bjornstad, Brian 2006
The Restless Northwest: A Geological Story by Williams
Roadside Geology of Washington by Alt & Hyndman 1994
Glacial Lake Missoula and its Humongous Floods by David Alt 2001
On the Trail of the Ice Age Floods The Northern Reaches A geological field guide to northern Idaho and the Channeled Scablland by Bjornstad, Bruce & Eugene Kiver 2012
Washington's Channeled Scablands Guide by Soennichsen, John
NOVA | Mystery of the Megaflood | Links & Books | PBS. www.pbs.org/wgbh/nova/megaflood/resources.html
http://www.oregongeology.org/pubs/ims/IMS-036_print.pdf