4 May 2010
Where on (Google) Earth #201 – hosted for JimmyJames
Posted by Jessica Ball
Having not posted anything for a while, I was trying to think up something non-taxing to write about (don’t want to take on too much on my birthday!) Fortunately, JimmyJames, the last winner of Wo(G)E, made it easy for me – he’s ready to reveal the next edition of Where on (Google) Earth! So here it is:
“This is my first win of Where on Google Earth and I’m honoured to be amongst the folks that participate in this contest. I should admit right away that I am not a geologist (nor indeed a blogger) but I have tried to make the WoGE #201 a challenging puzzle.
This edition of WoGE#201 reveals yet another attractive example of folded sedimentary strata.
As ever, to win WoGE find the Longitude and Latitude of the image, identify the country / area and describe the geological significance of the feature, then post this information in the Comments section below. The first one to post the correct information will go on to host the next edition of WoGE.
With respect, I’m invoking the (Ron) Shott rule: “Previous winners must wait at least one hour for each win that they have before posting a solution – other comments would be okay”.
Good luck to all of you! And a heartfelt thanks to ‘Tuff Cookie’ for hosting my post!
To compensate for the low res Google imagery, I have supplemented it with some higher resolution aerial orthophotos for your viewing pleasure.”
(Click to see the enlarged versions!)
Jessica Ball is a volcanologist at the U.S. Geological Survey, researching volcanic hydrothermal systems and stability, and doing science communication for the California Volcano Observatory. She previously worked at the Geological Society of America's Washington DC Policy Office, learning about the intersection of Earth science and legislative affairs. Her Mendenhall postdoc and PhD focused on how water affects the stability of volcanoes, and involved both field investigations and numerical modeling applications. Her blogging covers a range of topics, from her experiences in academic geosciences to science outreach and communication to her field and lab work in volcanology.
I hope it won't be considered a violation of the Schott Rule for me to not wait 48 hours to wish you a Happy Birthday, Jess! 🙂
Not at all! Thanks!
57.004 N 128.141 Wnorthwestern British ColumbiaAs Jimmy James shared with us, this spot has some really nice folded sedimentary strata, which you can barely make out in the Google Earth imagery. These folded rocks are part of the Stikine Terrane (I think), which is made of Carboniferous to Early Jurassic (320-190 Ma) island arc rocks that accreted to North America during the Middle Jurassic. Looking at the figures and introduction of Gaillardet et al. (2003, doi:10.1016/j.chemgeo.2003.07.001) it looks like the image might be from the Bowser sedimentary basin, where there are post-accretionary volcaniclastic greywackes, shales, sandstones, and some coal. There's also a Skeena Fold Belt in the southern part of that basin, which sounds like a promising explanation for the imagery. The Gaillardet et al. study looks at chemical weathering rates in that area and int he volcanic rocks of the terrane. I'll also point out that the area shows the dominant geomorphic influence of valley glaciation, with the broad and uneven valley bottoms.And Happy Birthday!!!
Congratulations Dr. Jefferson for a speedy (and humbling) answer to my challenge.The site is indeed a component of the northeast Bowser Basin (Skeena Fold Belt), a successor basin which overlays the Stikine Terrain. Specifically: inclined anticline / syncline folding, Skelhorne Assemblage (Deltaic), Bowser Lake Group, Bowser Basin.The location is: Kluayaz Creek/Lake, upper Skeena River watershed of Northwestern BC, Canada. The two air orthos are attributed to the Government of British Columbia, Ministry of Energy, Mines and Petroleum Resources and can be found publicly (no paywall) through the ImapBC online GIS using the Ortho TRIM 2 Photo Mosaic Black and White 1995-2003 (1m) layer.http://webmaps.gov.bc.ca/imfx/imf.jsp?site=imapbcThe BC Gov estimates that the Bowser Basin contains reserves of metallurgical coal at over 2 billion metric tons, coalbed methane reserves at over 3 trillion cubic feet and over 2 billion barrels of oil. Difficult geology (and sensitive watersheds) have limited both exploration and development. The WoGE#201 site is within 30km of both the Klappan and Groundhog coal deposits.Site description from the 2009 Geological Survey of Canada Compilation Map: Thinly intermixed and varicoloured siltstone, sandstone and conglomerate (with or without coal), commonly arranged in coarsening and thickening upward cycles, common features of sandstone are parallel bedding, crossbedding, ripples, burrows, bivalve coquina and brown, green and grey-weathered surfaces; congomerate is rusty and grey-weathering, but constitutes a lower proportion (15-30% of the unit than in the Eaglenest Assemblage; conglomerate units, up to 50m thick, cap styles up to 70m thick and tops locally have megaripples, plant and marine fossils are common and trace fossils including Skolithus and Diplocraterion are present as are tree fragments several metres long. – Open File 5794, Geological Survey of Canada; Evenchick, C.A., Mustard, P.S., McMechan, M.E., Greig, C.J., Ferri, F., Ritcey, D.H., Smith, G.T., Hadlari, T., and Waldron, J.W.F. (2009), Geological Compilation of Bowser and Sustut Basins Draped on Shaded Relief Map, North Central British Columbia, Geological Survey of Canada, NC Ministry of Energy, Mines and Petroleum Resources (2009-02)Geology compilation map (GSC; no paywall) link:http://tinyurl.com/235p6w7
Jessica, will you please correct my eroneous spelling of Stikine 'Terrain' to 'Terrane'. Thanks.
Blogger's too low-tech to let me – but duly noted!
Thank you Jimmy James for inspiring me to learn more about this area and then for providing even more context.WoGE #202 is now up at Highly Allochthonous