Posted on January 10, 2013 by magmatist
Broken surface of quartzite.
I’ve been asked about the source for the quartzite clasts in Puget Lowland glacial till. They are diagnostic of a British Columbian provenance for the Puget Lobe of the Vashon advance, and the great glaciations that preceeded that one. Go to the quartzite page, where I discuss the source for these pebbles, and attempt to confuse everyone because there are two kinds of quartzite.
Filed under: British Columbia geology, geology, glacial erratics, glacial geology, North Cascades geology | Tagged: Cariboo Mountains, Fragrance Lake Trail, glacial till, quartzite, Selkirk Mountains, Vashon till | 2 Comments »
Posted on December 14, 2012 by magmatist
The Christmas Girls had just finished decorating all the sign posts as I pulled into the parking lot. Very festive! Click to enlarge.
I’ve written up a geology guide to the popular Fragrance Lake trail. You’ll find it here. Even if the hike is mostly in glacial till, there are interesting stones in it, and the Chuckanut cliffs are always worth a peak. I do some armwaving about the origin of the big cliffs above the lake, too.
Filed under: Bellingham area, Chuckanut Formation, geologic structure, geology, Geology concepts, Geology field trips, glacial geology, North Cascades geology, sedimentary rocks, strike and dip | Tagged: Bellingham area things to do, Chuckanut Formation, Chuckanut Mountains, cobbles and pebbles, Fragrance Lake, geologic structure, Geology field trips, glacial till, hiking trails, Larrabee State Park, North Cascades geology, Pleistocene deposits, plunging syncline, strike and dip, Washington Geology | 1 Comment »
Posted on December 8, 2012 by magmatist
Hassan Basagic, a glacier researcher at Portland State University, has been making a series of comparative photos showing glacial changes in the Cascades. He came across the Loomis-Baker comparison photos taken by E.D. Welsh (1912) and John Scurlock (2012) and posted on the MBVRC website a couple of months ago. Hassan sent the photo below, showing the Boulder Glacier (left side) and Park Glacier (on the right) from 4640′ on Boulder Ridge, which extends eastward from Mount Baker between Boulder and Park Creeks. The upper photo was taken by J.E. Booen (also spelled ‘Boen’ in some documents) during the first ascent of the Boulder Glacier route by the ‘LaConnor Expedition’. Hassan’s documentation says the photo was taken in 1892, but according to John Miles’s account of this ascent in Koma Kulshan (a history of human involvement with Mount Baker), this ascent was made in 1891. Hassan’s photo was taken this past fall (2012). The retreat of the Boulder Glacier is remarkable. It is not possible to measure the length of recession, but the decrease in ice thickness is clearly many tens of meters.
Here’s a link to the earlier post showing glacier comparison photos by Alan Kearney.
1892 (’91?) and 2012 photos of Mount Baker’s east flank, showing profound glacial recession. Click to enlarge.
Filed under: glacial geology, glaciers, global climate change, Mount Baker, North Cascades geology | Tagged: Boulder Glacier, climate, climate change, glacial recession, glacier comparison photography, Koma Kulshan, LaConnor Expedition, Mount Baker, Mount Baker climbing history, North Cascades glaciers, Park Glacier, science | Leave a Comment »
Posted on November 10, 2012 by magmatist
Alan Kearney’s photos showing South Cascade Glacier’s retreat, 1981 to 2006. Click to enlarge.
I posted comparison photos last month showing 100 years of glacier recession on the south side of Mount Baker. (The fundraiser posters are still available- go to the preceding link.) My friend Alan Kearney has published similar comparison photos on his photography blog. Alan’s photo pairs show marked changes in glacial extent and thickness in just the past few decades of his mountaineering career. View his photos here: http://alankearneyphotography.blogspot.com/2012/11/local-ice-photographing-cascade-before.html
Much of Alan’s writing deals with photographic technique, which is interesting in itself. If all you want is glacier comparison photos, scroll down. There are several starting midway and going to the end.
Filed under: citizen science, glacial geology, glaciers, global climate change, Mount Baker Volcano Research Center, North Cascades geology | Tagged: Alan Kearney, climate change, Coleman Glacier, Easton Glacier, glacial recession, Inspiration Glacier, Le Conte Glacier, Mount Baker, north cascade glaciers, South Cascade Glacier | Leave a Comment »
Posted on October 28, 2012 by magmatist
The 1912 Welsh photo at top, and the 2012 Scurlock re-created photo below. Click to enlarge.
Mount Baker Volcano Research Center is selling 20 x 30 ” posters showing a fantastic 1912 photo of the entire south side of Mount Baker, and the re-created photograph taken by John Scurlock 100 years later. The photos were taken from the summit of Loomis Mountain, south of the volcano and show much detail. Glacial recession is remarkable. Hop on over to the MBVRC website to see the poster, see some details about changes that 100 years have wrought, and learn how to order one. PLEASE PASS THIS POST TO OTHERS to help raise funds for a good cause- the MBVRC research and scholarship fund.
Filed under: fundraising, glacial geology, glaciers, global climate change, John Scurlock, Mount Baker, Mount Baker Volcano Research Center, North West Geological Society | Tagged: climate change, E.D. Welsh, Easton Glacier, glacial recession, John Scurlock, Loomis Mountain, Mount Baker, Mount Baker Volcano Research Center, North Cascades glaciers, shrinking glaciers | Leave a Comment »
Posted on May 21, 2012 by magmatist
On the Trail of the Ice Age Floods: The Northern Reaches, by Bruce Bjornstad and Gene Kiver, is now published. The book directs readers to field sites in the the Channeled Scablands and into northern Idaho to see evidence for the mind-boggling late-Pleistocene Missoula Floods. There are hikes, road trips, and even two aerial field trips. The book is a sequel to On the Trail of the Ice Age Floods: A geological field guide to the Mid-Columbia Basin by Bruce Bjornstad. A description of the new book is available at the publishers’ website:
Filed under: books, Columbia River Basalt, flood erosion, floods and high water, Geology guide books, glacial geology, guided field trips | Tagged: Bruce Bjornstad, channeled scablands, Gene Kiver, Geology guide books, Missoula Floods, Washington Geology | Leave a Comment »
Posted on March 20, 2012 by magmatist
Greg shows off the cleaned-up Martha Lake erratic. Spic and span! photo courtesy of Greg Kulseth. Click to enlarge.
Greg Kulseth reports this morning that the graffiti has been removed from the Martha Lake Erratic at Martha Lake Airport Park. The Snohomish County Parks Department also put up an interpretive sign about erratics: where they come from, how they get swept up into glaciers, and the extent of the last glacial maximum. The sign mentions the Lake Steven’s Erratic, and states that it may be the largest in the US.
Special thanks to David McConnell of the Parks Department, who, last I heard, was going to spearhead the cleanup, and to Greg for sending the good news.
I’ve updated the Martha Lake erratic webpage to show the now-cleaned up boulder.
Looking at my calendar, I see it is ‘Spring’. Looking out my window- hmmm. Oh, there’s a new snowdrop blooming, and maybe a leaf bud! Guess the calendar isn’t that far off, and the precession of the equinox marches on.
Have a good spring!
Filed under: glacial erratics, glacial geology | Tagged: Geology field trips, glacial erratics, Martha Lake County Park, northwest geology | Leave a Comment »
Posted on March 8, 2012 by magmatist
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.
Filed under: glacial erratics, glacial geology | Tagged: Coupeville, Geology field trips, glacial erratics, northwest geology, Pleistocene deposits, Pleistocene deposits; Whidbey Island; geology, Waterman erratic, Wedgwood erratic, Whidbey Island | 4 Comments »
Posted on February 21, 2012 by magmatist
The granitic erratic at Highline Community College. Photo by Bud Hardwick.
Bud Hardwick sent photos and geographic information about a large granitic erratic (yes, another one of those dang things) at Shoreline Community College in Des Moines (Washington!). I looked closely at his photos and made some deductions about the geology. Take the virtual field trip to this erratic elsewhere on this website. The rock is notable because of the textbook en echelon dikes running the full length of the big erratic.
Also, the latest National Geographic has a photo essay on glacial erratics by Fritz Hoffman. Alas, none of the ones describe n this website or any others in western Washington are included, not even the Lake Stevens Monster, the largest in the whole country. See the photos here (an NPR website).
Filed under: glacial erratics, glacial geology | Tagged: alaskite, en echelon dikes, Geology field trips, glacial erratics, Highline Community College | 6 Comments »
Posted on January 26, 2012 by magmatist
The largest of several erratics on the north shore of Seattle's Discovery Park. Photo provided by Sandy Bowman.
A new field trip to visit some erratics on the north shore of Discovery Park is here. These were measured and photographed by Sandy Bowman and Consuela Larrabee. I confess I’ve been sitting on this report for months and months. This trip requires a hike on the North Beach Trail, and provides a nice excuse to get outside for a partial day’s outing.
Filed under: Geology field trips, glacial erratics, glacial geology | Leave a Comment »