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    Northwest Geology Field Trips, by Dave Tucker, is licensed under a Creative Commons Attribution-Noncommercial- Share Alike 3.0 United States License. You can use what you find here, repost it with attribution to the author, "remix" it for your own purposes, but may not use it with the intent of making money off of it.

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Coupeville’s Big Rock in the news

Big Rock. Island County Commissioner Angie Homola and her daughter Kira. Angie says she is 5 ft tall, so the erratic is about 22' (6.7 m) tall. 2010 photo by Dave Tucker.

Big Rock in the 1960s. Photo courtesy of Donn Charnley.

The big rounded erratic in Coupeville has recently been the subject of debate. The town council considered a proposal to purchase the land the erratic sits on to protect the rock from possible destruction. Their was concern that the owner of the apartments behind (to the west) of the rock would consider ‘removing’ the boulder to make room for a new and larger apartment complex. Here is the story in the Whidbey News Times. An earlier article in the paper, including information from UW glacial geologist Terry Swanson, describes the rock and the property ownership issue. The second article also reveals that at least as late as the 1930s, a stairway allowed access to the rock’s summit. Note that the newspaper refers to the big hunk o’ greenstone as ‘granite’, though a much earlier story in a rival newspaper (South Whidbey Record), identified the rock correctly in an article about erratics featuring Terry Swanson.

The Wedgwood erratic is on a lot cared for by the neighborhood.

Thanks to Valarie Bunn of Seattle’s Wedgwood neighborhood for supplying these links. She wrote about the similar Wedgwood erratic in her Wedgwood history blog.

Samish Hill slab- a curtain call.

By Dave Tucker

Saturday, July 31, 2010

Grandson Alec Foote at the site Saturday 7/31/10. Click to enlarge any image.

Construction has nearly completely destroyed the glacially smoothed and striated slab on Samish Hill in Bellingham. The site was featured in a March posting. Now there is an 8-foot-deep pit blasted into coarse facies of the Chuckanut Formation; this will be the home of the new Temple Beth El synagogue. A few interesting sites remain to be seen: coal seams, curiously-textured very coarse-grained sandstone, some coalified fossil branches. If the big yellow tracked crusher is still there, that is worth a look-see. The erratics discussed in the previous story are still there, though getting overgrown by high field grass. TH SITE FEATURED ON THIS FIELD TRIP WILL LIKELY BE GONE WITHIN DAYS, SO DO NOT DELAY. It makes for a quick outing, an hour at most on a sunny day (well, it was sunny when I started this!) this weekend.

How to find the 'Samish Slab'. Click to enlarge

Getting there: These are new directions, as access through the construction entrance is less feasable now. Begin at a foot trail on City of Bellingham right of way at the south end of 47th Street. The trail, ‘paved’ with poorly sorted glacial drift, goes south through shaded and pleasantly cool second [third?] growth forest. Turn left at a T-junction after about 200 yards. The trail ascends slightly, and shortly comes to a nexus of several trails. The construction site is visible off to the left, but instead of crossing over the ‘no trespassing’ sign, continue straight on a trail with low bushes to the left between you and the construction site. You will see one or more faint tracks going left a few feet into the grassy construction clearing. Walk east (right) along the fence at the top of the pit. If there is no work going on, you’ll figure out how to get down into the pit.

The upper part of the drill hole is in competent, fine sandstone. When it entered the poorly cemented coarser sediment, the hole sheared.

Once in the pit, examine the SE corner to see the remnant of a blasting drill hole. At the top, it is smooth and half-round, but lower down, it enters a very friable coarse granule layer and becomes very distorted due to incompetence of the lower rock layer; the drill must have crushed its way through this layer before reentering solid sandstone beneath it. Just to the left are a couple of small coal seams. Walk along the south face of the pit wall and watch for some coalified wood. At the SW corner, a cross section reveals smooth glacial till overlying the ice-planed smooth surface of the slab- an unconformity representing around 50 million years of missing time. This smooth rock surface is about all that is left of the once very extensive striated surface of the Samish Slab.

Till overlies the glacially smoothed erosional surface of Chuckanut Formation sandstone. Alec's hand is on a 50 million-year unconformity

Fay, Alec's 1-foot-long pug, for scale at the coalified wood exposure.

I climbed up onto to the big, yellow, tracked, crusher beside the big pile of crushed rock. This heap is all that is left of the rock that filled the excavation. The climb up was not simple, but the big jaws are very impressive. If you have seen a rock crusher in a geology lab, you’ll be doubly impressed at the comparison.

The tracked crusher with Alec and Fay.

Jaw crusher

Whidbey Island glacial stratigraphy series begun

I have published the first in a series of field trips to Whidbey Island beaches that expose late-Pleistocene glacial and interglacial sediments. The first one visits the west shore of Useless Bay and Double Bluff, where you can also see fabulous liquifaction features interpreted to result from earthquakes along the South Whidbey fault.

The next trip will go to Blower’s Bluff. I have visited and gotten photos, and will write it up soon. Please subscribe to this website if you want to know when I have posted it.

DT