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<channel>
	<title>Mountain Beltway</title>
	<atom:link href="http://blogs.agu.org/mountainbeltway/feed/" rel="self" type="application/rss+xml" />
	<link>http://blogs.agu.org/mountainbeltway</link>
	<description>By Callan Bentley</description>
	<lastBuildDate>Fri, 17 May 2013 12:58:02 +0000</lastBuildDate>
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		<item>
		<title>Friday fold: Rorschach blot</title>
		<link>http://blogs.agu.org/mountainbeltway/2013/05/17/friday-fold-rorschach-blot/</link>
		<comments>http://blogs.agu.org/mountainbeltway/2013/05/17/friday-fold-rorschach-blot/#comments</comments>
		<pubDate>Fri, 17 May 2013 12:58:02 +0000</pubDate>
		<dc:creator>Callan</dc:creator>
				<category><![CDATA[british columbia]]></category>
		<category><![CDATA[canada]]></category>
		<category><![CDATA[folds]]></category>
		<category><![CDATA[Friday Fold]]></category>
		<category><![CDATA[national parks]]></category>

		<guid isPermaLink="false">http://blogs.agu.org/mountainbeltway/?p=10885</guid>
		<description><![CDATA[The broad symmetry (with smaller-scale variations) of this fold caught my eye as particularly artful when I saw it (at Howard&#8217;s recommendation) last summer in the Canadian Rockies: Kootenay National Park, British Columbia, Canada. I see a butterfly. What do you see? Happy Friday.]]></description>
			<content:encoded><![CDATA[<p>The broad symmetry (with smaller-scale variations) of this fold caught my eye as particularly artful when I saw it (<a href="http://blogs.agu.org/mountainbeltway/2011/08/19/friday-fold-one-from-walcott/#comment-3071">at Howard&#8217;s recommendation</a>) last summer in the Canadian Rockies:</p>
<p><img class="alignnone  wp-image-10886" title="rorschach" src="http://blogs.agu.org/mountainbeltway/files/2013/05/rorschach.jpg" alt="" width="650" height="366" /><em>Kootenay National Park, British Columbia, Canada.</em></p>
<p>I see a butterfly. What do you see?</p>
<p>Happy Friday.</p>
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		<item>
		<title>GigaPanning Kilbourne Hole</title>
		<link>http://blogs.agu.org/mountainbeltway/2013/05/16/gigapanning-kilbourne-hole/</link>
		<comments>http://blogs.agu.org/mountainbeltway/2013/05/16/gigapanning-kilbourne-hole/#comments</comments>
		<pubDate>Thu, 16 May 2013 13:09:33 +0000</pubDate>
		<dc:creator>Callan</dc:creator>
				<category><![CDATA[gigapan]]></category>
		<category><![CDATA[m.a.g.i.c.]]></category>
		<category><![CDATA[new mexico]]></category>
		<category><![CDATA[texas]]></category>
		<category><![CDATA[volcano]]></category>
		<category><![CDATA[xenoliths]]></category>

		<guid isPermaLink="false">http://blogs.agu.org/mountainbeltway/?p=10876</guid>
		<description><![CDATA[Kilbourne Hole is the crater of a maar volcano in southern New Mexico, just across the state line from El Paso, Texas. I went there the weekend before last with a team from El Paso Community College, led by Joshua Villalobos. This is the place where xenobombs come from! If you go to the right area, you can find dozens of these mantle xenoliths sheathed in fine-grained basalt, like chocolate-coated &#8230;]]></description>
			<content:encoded><![CDATA[<p>Kilbourne Hole is the crater of a maar volcano in southern New Mexico, just across the state line from El Paso, Texas.</p>
<p><img class="alignnone size-full wp-image-10879" title="khole" src="http://blogs.agu.org/mountainbeltway/files/2013/05/khole.jpg" alt="" width="650" height="436" /></p>
<p>I went there the weekend before last with a team from El Paso Community College, led by Joshua Villalobos. This is the place where <a href="http://blogs.agu.org/mountainbeltway/2012/02/18/the-xenobomb/">xenobombs</a> come from!</p>
<p><img class="alignnone size-full wp-image-10880" title="xeno" src="http://blogs.agu.org/mountainbeltway/files/2013/05/xeno.jpg" alt="" width="650" height="857" /></p>
<p>If you go to the right area, you can find dozens of these mantle xenoliths sheathed in fine-grained basalt, like chocolate-coated peanuts. There are also lower crustal xenoliths; gneisses and stuff like that. But nothing beats peridotite for sheer &#8216;otherworldly&#8217; beauty and awe.</p>
<p>We also saw these beautiful outcrops of volcanic blocks that got ker-plumped down into the pyroclastic surge deposits:</p>
<p><img class="alignnone size-full wp-image-10877" title="drop1" src="http://blogs.agu.org/mountainbeltway/files/2013/05/drop1.jpg" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10881" title="drop2" src="http://blogs.agu.org/mountainbeltway/files/2013/05/drop2.jpg" alt="" width="650" height="488" /></p>
<p>Ron Schott produced a wonderful overview GigaPan of the site back in 2009:<br />
<iframe src="http://gigapan.org/gigapans/43663/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/43663">link</a></p>
<p>So rather than the broad landscape, we concentrated our efforts on smaller outcrops, like this informative scene:<br />
<iframe src="http://gigapan.org/gigapans/129481/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/129481">link</a></p>
<p>Annotated:<br />
<iframe src="http://gigapan.org/gigapans/129892/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/129892">link</a></p>
<p>Same place, zoomed out a bit, and from a higher perspective (and a bit overexposed):<br />
<iframe src="http://gigapan.org/gigapans/129419/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/129419">link</a></p>
<p>Annotated:<br />
<iframe src="http://gigapan.org/gigapans/129891/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/129891">link</a></p>
<p>Now for the really sexy stuff! Here is one of those volcanic block plopped like a dropstone into the pyroclastics:<br />
<iframe src="http://gigapan.org/gigapans/129483/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/129483">link</a></p>
<p>Another, similar scene&#8230;<br />
<iframe src="http://gigapan.org/gigapans/129453/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/129453">link</a></p>
<p>And closer in:<br />
<iframe src="http://gigapan.org/gigapans/129454/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/129454">link</a></p>
<p>I trained Josh and his students on the use of their new GigaPan, and we had a great time. Here&#8217;s the El Paso CC / UTEP team on the rim of the Hole:<br />
<img class="alignnone size-full wp-image-10878" title="edge" src="http://blogs.agu.org/mountainbeltway/files/2013/05/edge.jpg" alt="" width="650" height="488" /></p>
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		<title>Dark Star Safari by Paul Theroux</title>
		<link>http://blogs.agu.org/mountainbeltway/2013/05/15/dark-star-safari-by-paul-theroux/</link>
		<comments>http://blogs.agu.org/mountainbeltway/2013/05/15/dark-star-safari-by-paul-theroux/#comments</comments>
		<pubDate>Wed, 15 May 2013 12:40:49 +0000</pubDate>
		<dc:creator>Callan</dc:creator>
				<category><![CDATA[africa]]></category>
		<category><![CDATA[books]]></category>
		<category><![CDATA[policies & politics]]></category>
		<category><![CDATA[travel]]></category>

		<guid isPermaLink="false">http://blogs.agu.org/mountainbeltway/?p=10829</guid>
		<description><![CDATA[The week before last, on the flight home from Texas, I finished reading Dark Star Safari, Paul Theroux&#8217;s 2004 account of traveling overland through Africa from Cairo to Cape Town. I&#8217;ve enjoyed Theroux&#8217;s traveling writing very much over the years, and although he&#8217;s written some great novels (I&#8217;m thinking of Mosquito Coast), most of them don&#8217;t appeal to me as much as the travelogues do. I&#8217;ve been reading a lot &#8230;]]></description>
			<content:encoded><![CDATA[<p><img class="alignright size-full wp-image-10868" title="dss" src="http://blogs.agu.org/mountainbeltway/files/2013/05/dss.jpg" alt="" width="318" height="500" />The week before last, on the flight home from Texas, I finished reading <em>Dark Star Safari</em>, Paul Theroux&#8217;s 2004 account of traveling overland through Africa from Cairo to Cape Town. I&#8217;ve enjoyed Theroux&#8217;s traveling writing very much over the years, and although he&#8217;s written some great novels (I&#8217;m thinking of <em>Mosquito Coast</em>), most of them don&#8217;t appeal to me as much as the travelogues do.</p>
<p>I&#8217;ve been reading a lot lately, but most of it has been for book reviews that will be published in upcoming issues of <em>Earth</em> magazine. But this one has been on my shelf for a while, and I&#8217;ve been meaning to read it since it was published nine years ago. I enjoyed it. I&#8217;ve taken three trips to Africa in my life: Namibia in winter of 1996-7, Tanzania and Kenya in summer 2002, and then South Africa most recently in the winter of 2011-2012. Three of those four countries were on Theroux&#8217;s route south (see map below).</p>
<p>Why read a travelogue like this? For me, it&#8217;s an easy way to dip into the experience of travel (the good, the bad, the ugly) without any of the hassle or risk. Theroux gets into some hairy situations, and he ventures to inhospitable places &#8211; the real Africa, off the tourists&#8217; well-beaten path. I like reading about decision-making as to logistics of how to get from point A to point B, or solving the problems of being away from home, out experiencing the world. I like the commiseration I feel when I read of Theroux crammed into a matatu with a dozen other people, of dealing with intestinal distress abroad, of arguing with mean-spirited people. All are familiar experiences to the traveler in Africa, and the great thing about a travelogue is that you can close the book and turn out the light when you want. Unlike actually being there, there&#8217;s nothing to compel you to resolve things ASAP, and for some reason, I like that.</p>
<p>The chief take-away message from the book is one of policy. Wherever Theroux traipses in East Africa, he finds do-gooders from the West mucking things up. He concludes that Western aid to Africa ultimately does more harm than good, as it enables corrupt government and encourages a &#8220;handout&#8221; mentality. Whether you agree with that assessment is of course up to you, but I&#8217;ve got to admit that he makes a pretty compelling case, with anecdotes and interviews aplenty as evidence. The most heartbreaking part of the book is when he revisits his former Peace Corps site in Malawi. There, he finds his old school in ruins, ransacked and gutted by thievery and disrespect. Some of his former students are now government ministers, and he gets together with them to bemoan the country&#8217;s descent into squalor. <a href="http://blogs.agu.org/mountainbeltway/files/2013/05/dssmap.jpg"><img class="alignleft size-full wp-image-10869" title="dssmap" src="http://blogs.agu.org/mountainbeltway/files/2013/05/dssmap.jpg" alt="" width="281" height="354" /></a>He effectively conveys the sense of how the good work he thought he was doing in the 1960s &#8212; the promise he felt, the sense of hope and forward momentum &#8212; is totally lost, and the country&#8217;s economy and character have become mired in a lack of ambition, victimization by the world economy, and drained of vitality by the too-close association of neighbors. As a returned Peace Corps Volunteer myself (Mongolia, 1998-99), I found this fascinating. As a traveler to Africa, I found it dispiriting and authentic.</p>
<p>Overall, the book wasn&#8217;t as fascinating a journey as some of his other books, and I think that&#8217;s because it was a more personal book &#8211; a return to one of the formative experiences of his own life, and thus there was a modicum of navel-gazing i<em>n Dark Star Safari</em> that I didn&#8217;t get from T<em>he Great Railway Bazaar </em>or<em> The Happy Isles of Oceania</em>. I don&#8217;t feel like I learned much that was &#8216;exotic&#8217; and interesting about Africa (history, anthropology, geography), but instead the book does an effective job painting a picture of sad stasis and decay, of failed policies and crowded conditions in the cradle of our species.</p>
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		<item>
		<title>An itty bitty brachiopod</title>
		<link>http://blogs.agu.org/mountainbeltway/2013/05/14/an-itty-bitty-brachiopod/</link>
		<comments>http://blogs.agu.org/mountainbeltway/2013/05/14/an-itty-bitty-brachiopod/#comments</comments>
		<pubDate>Tue, 14 May 2013 12:05:47 +0000</pubDate>
		<dc:creator>Callan</dc:creator>
				<category><![CDATA[devonian]]></category>
		<category><![CDATA[fossils]]></category>
		<category><![CDATA[valley and ridge]]></category>
		<category><![CDATA[virginia]]></category>

		<guid isPermaLink="false">http://blogs.agu.org/mountainbeltway/?p=10821</guid>
		<description><![CDATA[Found this small, flat brachiopod fossil last fall just down the road from my place in the Fort Valley. Lovely little thing&#8230; That&#8217;s all I&#8217;ve got for you today!]]></description>
			<content:encoded><![CDATA[<p>Found this small, flat brachiopod fossil last fall just down the road from my place in the Fort Valley. Lovely little thing&#8230;</p>
<p><img class="alignnone size-full wp-image-10822" title="brach" src="http://blogs.agu.org/mountainbeltway/files/2013/05/brach.jpg" alt="" width="650" height="515" /></p>
<p>That&#8217;s all I&#8217;ve got for you today!</p>
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		<slash:comments>1</slash:comments>
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		<title>Monday macrobug: Flight of the termites</title>
		<link>http://blogs.agu.org/mountainbeltway/2013/05/13/monday-macrobug-flight-of-the-termites/</link>
		<comments>http://blogs.agu.org/mountainbeltway/2013/05/13/monday-macrobug-flight-of-the-termites/#comments</comments>
		<pubDate>Mon, 13 May 2013 12:14:29 +0000</pubDate>
		<dc:creator>Callan</dc:creator>
				<category><![CDATA[arthropods]]></category>
		<category><![CDATA[home]]></category>
		<category><![CDATA[insects]]></category>

		<guid isPermaLink="false">http://blogs.agu.org/mountainbeltway/?p=10807</guid>
		<description><![CDATA[Termites can fly. But not all termites. Around here, the only flying termites are the reproductives &#8211; the fertile males and females that a termites colony produces periodically. It seems to be associated with the advent of spring. I spotted this group a couple of weeks ago, when I noticed the sunlight catching in their diaphanous wings. They hatch, emerge en masse, and take to the air, seeking a partner &#8230;]]></description>
			<content:encoded><![CDATA[<p>Termites can fly.</p>
<p>But not all termites.</p>
<p>Around here, the only flying termites are the reproductives &#8211; the fertile males and females that a termites colony produces periodically. It seems to be associated with the advent of spring.</p>
<p><img class="alignnone size-full wp-image-10808" title="ants01" src="http://blogs.agu.org/mountainbeltway/files/2013/05/ants01.gif" alt="" width="650" height="617" /></p>
<p>I spotted this group a couple of weeks ago, when I noticed the sunlight catching in their diaphanous wings.</p>
<p><img class="alignnone size-full wp-image-10809" title="ants1" src="http://blogs.agu.org/mountainbeltway/files/2013/05/ants1.gif" alt="" width="650" height="680" /></p>
<p>They hatch, emerge <em>en masse</em>, and take to the air, seeking a partner of the opposite sex.</p>
<p><img class="alignnone size-full wp-image-10810" title="ants02" src="http://blogs.agu.org/mountainbeltway/files/2013/05/ants02.gif" alt="" width="650" height="597" /></p>
<p>It&#8217;s a busy scene when they emerge &#8211; lots of termites, lots of wing fluttering.</p>
<p><img class="alignnone size-full wp-image-10811" title="ants2" src="http://blogs.agu.org/mountainbeltway/files/2013/05/ants2.gif" alt="" width="650" height="516" /></p>
<p>Once they have mated, they jettison their wings, and the female crawls underground (or into a suitable piece of wood?) to inoculate a new colony.</p>
<p>Stay away from my house, termites!</p>
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		<title>The latest flood on Passage Creek</title>
		<link>http://blogs.agu.org/mountainbeltway/2013/05/11/the-latest-flood-on-passage-creek/</link>
		<comments>http://blogs.agu.org/mountainbeltway/2013/05/11/the-latest-flood-on-passage-creek/#comments</comments>
		<pubDate>Sat, 11 May 2013 13:05:00 +0000</pubDate>
		<dc:creator>Callan</dc:creator>
				<category><![CDATA[floods]]></category>
		<category><![CDATA[gigapan]]></category>
		<category><![CDATA[home]]></category>
		<category><![CDATA[m.a.g.i.c.]]></category>
		<category><![CDATA[valley and ridge]]></category>
		<category><![CDATA[virginia]]></category>

		<guid isPermaLink="false">http://blogs.agu.org/mountainbeltway/?p=10826</guid>
		<description><![CDATA[We had another flood on Passage Creek on Wednesday, and into Thursday morning. Here are a few photos and GigaPans for those of you who like flood imagery: link link link Making GigaPans of the scene: Some images of the flood itself: Aftermath: http://www.gigapan.com/gigapans/129490 http://www.gigapan.com/gigapans/129543 http://www.gigapan.com/gigapans/129569 10.3 feet  was the maximum gauge height this time (6 is bridge level), which means the stream is putting out 4200 cubic feet of &#8230;]]></description>
			<content:encoded><![CDATA[<p>We had another flood on Passage Creek on Wednesday, and into Thursday morning. Here are a few photos and GigaPans for those of you who like flood imagery:</p>
<p><iframe src="http://gigapan.org/gigapans/129543/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/129543">link</a></p>
<p><iframe src="http://gigapan.org/gigapans/129490/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/129490">link</a></p>
<p><iframe src="http://gigapan.org/gigapans/129569/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/129569">link</a></p>
<p>Making GigaPans of the scene:</p>
<p><img class="alignnone size-full wp-image-10857" title="floods_bug19" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug19.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10855" title="floods_bug17" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug17.gif" alt="" width="650" height="741" /></p>
<p><img class="alignnone size-full wp-image-10856" title="floods_bug18" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug18.gif" alt="" width="650" height="488" /></p>
<p>Some images of the flood itself:</p>
<p><img class="alignnone size-full wp-image-10847" title="floods_bug09" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug09.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10848" title="floods_bug10" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug10.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10849" title="floods_bug11" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug11.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10853" title="floods_bug15" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug15.gif" alt="" width="650" height="867" /></p>
<p><img class="alignnone size-full wp-image-10850" title="floods_bug12" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug12.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10854" title="floods_bug16" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug16.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10852" title="floods_bug14" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug14.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10851" title="floods_bug13" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug13.gif" alt="" width="650" height="488" /></p>
<p>Aftermath:</p>
<p><img class="alignnone size-full wp-image-10858" title="floods_bug20" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug20.gif" alt="" width="650" height="488" /></p>
<p>http://www.gigapan.com/gigapans/129490 http://www.gigapan.com/gigapans/129543 http://www.gigapan.com/gigapans/129569</p>
<p><img class="alignnone size-full wp-image-10863" title="floods_bug25" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug25.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10862" title="floods_bug24" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug24.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10861" title="floods_bug23" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug23.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10860" title="floods_bug22" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug22.gif" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10846" title="floods_bug26" src="http://blogs.agu.org/mountainbeltway/files/2013/05/floods_bug26.gif" alt="" width="650" height="488" /></p>
<p>10.3 feet  was the maximum gauge height this time (6 is bridge level), which means the stream is putting out 4200 cubic feet of discharge per second.</p>
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		<title>Friday fold: New Market / Lincolnshire formation contact, Staunton, Virginia</title>
		<link>http://blogs.agu.org/mountainbeltway/2013/05/10/friday-fold-new-market-lincolnshire-formation-contact-staunton-virginia/</link>
		<comments>http://blogs.agu.org/mountainbeltway/2013/05/10/friday-fold-new-market-lincolnshire-formation-contact-staunton-virginia/#comments</comments>
		<pubDate>Fri, 10 May 2013 12:12:39 +0000</pubDate>
		<dc:creator>Callan</dc:creator>
				<category><![CDATA[folds]]></category>
		<category><![CDATA[foliation]]></category>
		<category><![CDATA[fossils]]></category>
		<category><![CDATA[Friday Fold]]></category>
		<category><![CDATA[gigapan]]></category>
		<category><![CDATA[limestone]]></category>
		<category><![CDATA[m.a.g.i.c.]]></category>
		<category><![CDATA[structure]]></category>
		<category><![CDATA[valley and ridge]]></category>
		<category><![CDATA[virginia]]></category>

		<guid isPermaLink="false">http://blogs.agu.org/mountainbeltway/?p=10727</guid>
		<description><![CDATA[Happy Friday! Here&#8217;s a view of the folded contact between the (older, lower) New Market Formation, and the (younger, upper) Lincolnshire Formation, as exposed in Staunton, Virginia: The contact has been folded, pretty intensely: The New Market Formation is massive, light-colored, and exhibits fenestral texture here. The Lincolnshire is darker, more thinly-bedded, and is chock full of fossil invertebrates. Explore it for yourself in this M.A.G.I.C. GigaPan: link A closer &#8230;]]></description>
			<content:encoded><![CDATA[<p>Happy Friday! Here&#8217;s a view of the folded contact between the (older, lower) New Market Formation, and the (younger, upper) Lincolnshire Formation, as exposed in Staunton, Virginia:</p>
<p><img class="alignnone  wp-image-10731" title="stauntonfold02" src="http://blogs.agu.org/mountainbeltway/files/2013/04/stauntonfold02.jpg" alt="" width="650" height="488" /></p>
<p>The contact has been folded, pretty intensely:</p>
<p><img class="alignnone size-full wp-image-10732" title="stauntonfold03" src="http://blogs.agu.org/mountainbeltway/files/2013/04/stauntonfold03.jpg" alt="" width="650" height="488" /></p>
<p><img class="alignnone size-full wp-image-10739" title="stauntonfold03anno" src="http://blogs.agu.org/mountainbeltway/files/2013/05/stauntonfold03anno.jpg" alt="" width="650" height="488" /></p>
<p>The New Market Formation is massive, light-colored, and exhibits fenestral texture here. The Lincolnshire is darker, more thinly-bedded, and is chock full of fossil invertebrates.</p>
<p>Explore it for yourself in this M.A.G.I.C. GigaPan:</p>
<p><iframe src="http://gigapan.org/gigapans/128611/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/128611">link</a></p>
<p>A closer look at the folds is next&#8230;</p>
<p><img class="alignnone size-full wp-image-10730" title="stauntonfold01" src="http://blogs.agu.org/mountainbeltway/files/2013/04/stauntonfold01.jpg" alt="" width="650" height="789" /></p>
<p><img class="alignnone size-full wp-image-10736" title="stauntonfold07" src="http://blogs.agu.org/mountainbeltway/files/2013/04/stauntonfold07.jpg" alt="" width="650" height="867" /></p>
<p>And now, some close-ups showing the fossils in the Lincolnshire Formation:</p>
<p><img class="alignnone size-full wp-image-10733" title="stauntonfold04" src="http://blogs.agu.org/mountainbeltway/files/2013/04/stauntonfold04.jpg" alt="" width="650" height="406" /></p>
<p><img class="alignnone size-full wp-image-10734" title="stauntonfold05" src="http://blogs.agu.org/mountainbeltway/files/2013/04/stauntonfold05.jpg" alt="" width="650" height="724" /></p>
<p><img class="alignnone size-full wp-image-10735" title="stauntonfold06" src="http://blogs.agu.org/mountainbeltway/files/2013/04/stauntonfold06.jpg" alt="" width="650" height="458" /></p>
<p>Mostly bryozoans, as far as I can tell&#8230;</p>
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		<title>Boudinage in northern Minnesota</title>
		<link>http://blogs.agu.org/mountainbeltway/2013/05/09/boudinage-in-northern-minnesota/</link>
		<comments>http://blogs.agu.org/mountainbeltway/2013/05/09/boudinage-in-northern-minnesota/#comments</comments>
		<pubDate>Thu, 09 May 2013 12:35:21 +0000</pubDate>
		<dc:creator>Callan</dc:creator>
				<category><![CDATA[archean]]></category>
		<category><![CDATA[boudinage]]></category>
		<category><![CDATA[granite]]></category>
		<category><![CDATA[minnesota]]></category>
		<category><![CDATA[structure]]></category>
		<category><![CDATA[xenoliths]]></category>

		<guid isPermaLink="false">http://blogs.agu.org/mountainbeltway/?p=10795</guid>
		<description><![CDATA[This is my final post on the pre-GSA-Minneapolis structural geology field trip to the Superior Province. The photo above shows a roadcut exposure of boudinage in xenolith-bearing Vermillion Granitic Complex. Here&#8217;s another, smaller, more brittle example of boudinage, from another site, the following morning: Gee, it only took me 1.5 years to blog that trip in its entirety&#8230; Sheesh!]]></description>
			<content:encoded><![CDATA[<p><img class="alignnone size-full wp-image-10797" title="superior02" src="http://blogs.agu.org/mountainbeltway/files/2013/04/superior02.jpg" alt="" width="650" height="611" /></p>
<p>This is my final post on the pre-GSA-Minneapolis structural geology field trip to the Superior Province. The photo above shows a roadcut exposure of boudinage in xenolith-bearing Vermillion Granitic Complex.</p>
<p>Here&#8217;s another, smaller, more brittle example of boudinage, from another site, the following morning:</p>
<p><img class="alignnone size-full wp-image-10798" title="superior06" src="http://blogs.agu.org/mountainbeltway/files/2013/04/superior06.jpg" alt="" width="650" height="312" /></p>
<p><img class="alignnone size-full wp-image-10796" title="superior06anno" src="http://blogs.agu.org/mountainbeltway/files/2013/04/superior06anno.jpg" alt="" width="650" height="312" /></p>
<p>Gee, it only took me 1.5 years to blog that trip in its entirety&#8230; Sheesh!</p>
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		<title>A comparative look at the Klingle Valley outcrop</title>
		<link>http://blogs.agu.org/mountainbeltway/2013/05/08/a-comparative-look-at-the-klingle-valley-outcrop/</link>
		<comments>http://blogs.agu.org/mountainbeltway/2013/05/08/a-comparative-look-at-the-klingle-valley-outcrop/#comments</comments>
		<pubDate>Wed, 08 May 2013 11:18:01 +0000</pubDate>
		<dc:creator>Callan</dc:creator>
				<category><![CDATA[dc]]></category>
		<category><![CDATA[gigapan]]></category>
		<category><![CDATA[granite]]></category>
		<category><![CDATA[m.a.g.i.c.]]></category>
		<category><![CDATA[metamorphism]]></category>
		<category><![CDATA[sediment]]></category>
		<category><![CDATA[shear zones]]></category>

		<guid isPermaLink="false">http://blogs.agu.org/mountainbeltway/?p=10801</guid>
		<description><![CDATA[A week ago, I featured six new GigaPans here, of the extraordinary rocks in Klingle Valley, DC. I hadn&#8217;t been able to get the next phase of imaging that site ready in time for the post, but here it is: an annotated view of the outcrop. Annotation color code: PINK = Granite contact BLUE = Sericite after staurolite pseudomorphs YELLOW = Outlines of stretched clasts within the metaconglomerate GREEN = &#8230;]]></description>
			<content:encoded><![CDATA[<p><a href="http://blogs.agu.org/mountainbeltway/2013/04/30/strained-metaconglomerate-in-klingle-valley-dc/">A week ago, I featured six new GigaPans here, of the extraordinary rocks in Klingle Valley, DC</a>.</p>
<p>I hadn&#8217;t been able to get the next phase of imaging that site ready in time for the post, but here it is: an annotated view of the outcrop.</p>
<p><a href="http://www.gigamacro.com/gigamacro_viewer/gigamacro_comparative_viewer.php?view_mode=double&amp;image1_source=gigapan&amp;image1_id=128534&amp;image1_url&amp;image1_image_width_mm&amp;image2_source=gigapan&amp;image2_id=128969&amp;image2_url&amp;image2_image_width_mm"><img class="alignnone size-full wp-image-10802" title="anno-klingle2" src="http://blogs.agu.org/mountainbeltway/files/2013/05/anno-klingle2.jpg" alt="" width="650" height="340" /></a></p>
<p>Annotation color code:</p>
<p style="padding-left: 30px;"><span style="color: #ff00ff;"><strong>PINK</strong></span> = Granite contact<br />
<span style="color: #00ffff;"><strong>BLUE</strong></span> = Sericite after staurolite pseudomorphs<br />
<mark><span style="color: #ffff00;"><span style="color: #000000;"><strong>YELLOW</strong></span></span></mark> = Outlines of stretched clasts within the metaconglomerate<br />
<span style="color: #00ff00;"><strong>GREEN</strong></span> = Edges of lichens growing on the surface of the outcrop</p>
<p>Comparative viewer screenshot and link, so you can explore it for yourself:</p>
<p><a href="http://www.gigamacro.com/gigamacro_viewer/gigamacro_comparative_viewer.php?view_mode=double&amp;image1_source=gigapan&amp;image1_id=128534&amp;image1_url&amp;image1_image_width_mm&amp;image2_source=gigapan&amp;image2_id=128969&amp;image2_url&amp;image2_image_width_mm"><img class="alignnone size-full wp-image-10803" title="anno-klingle3" src="http://blogs.agu.org/mountainbeltway/files/2013/05/anno-klingle3.jpg" alt="" width="650" height="521" /></a></p>
<p>Pretty cool, eh?</p>
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		<title>Brallier Formation 2: tectonic structures</title>
		<link>http://blogs.agu.org/mountainbeltway/2013/05/07/brallier-formation-2-tectonic-structures/</link>
		<comments>http://blogs.agu.org/mountainbeltway/2013/05/07/brallier-formation-2-tectonic-structures/#comments</comments>
		<pubDate>Tue, 07 May 2013 11:33:43 +0000</pubDate>
		<dc:creator>Callan</dc:creator>
				<category><![CDATA[devonian]]></category>
		<category><![CDATA[faults]]></category>
		<category><![CDATA[folds]]></category>
		<category><![CDATA[joints]]></category>
		<category><![CDATA[minerals]]></category>
		<category><![CDATA[pennsylvanian (carboniferous)]]></category>
		<category><![CDATA[permian]]></category>
		<category><![CDATA[structure]]></category>
		<category><![CDATA[valley and ridge]]></category>
		<category><![CDATA[virginia]]></category>

		<guid isPermaLink="false">http://blogs.agu.org/mountainbeltway/?p=10778</guid>
		<description><![CDATA[Yesterday we examined primary sedimentary structures (including trace fossils) at an outcrop of Devonian-aged Brallier Formation turbidites between Deerfield and West Augusta, Virginia. Today, we&#8217;ll zoom in on the tectonic structures at the site: folds, faults, and joints. Remember, you don&#8217;t have to take my word for it. You can explore it for yourself in this M.A.G.I.C. GigaPan: link One thing that&#8217;s kind of cool about that GigaPan is the &#8230;]]></description>
			<content:encoded><![CDATA[<p>Yesterday we examined <a href="http://blogs.agu.org/mountainbeltway/2013/05/06/brallier-formation-1-primary-structures">primary sedimentary structures (including trace fossils)</a> at an outcrop of Devonian-aged Brallier Formation turbidites between Deerfield and West Augusta, Virginia. Today, we&#8217;ll zoom in on the tectonic structures at the site: folds, faults, and joints.</p>
<p>Remember, you don&#8217;t have to take my word for it. You can explore it for yourself in this M.A.G.I.C. GigaPan:</p>
<p><iframe src="http://gigapan.org/gigapans/128612/options/nosnapshots,hidetitle/iframe/flash.html" frameborder="0" height="250" scrolling="no" width="100%"></iframe> <a href="http://gigapan.org/gigapans/128612">link</a></p>
<p>One thing that&#8217;s kind of cool about that GigaPan is the very subtle view of folding. Note the the prominent sand stratum (a big turbidite) dips away from us on the left side of the outcrop, but twists about halfway across, and dips moderately toward the viewer on the right. It&#8217;s subtle because we&#8217;re not viewing the fold in profile view (<em>i.e.</em>, on an exposure orthogonal to the fold hinge). Instead, the outcrop face is oblique to, and almost parallel to, the hinge. Here is a different view, from a hundred yards north up the road, and here the fold is more obvious:</p>
<p><img class="alignnone size-full wp-image-10789" title="brallier19" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier19.jpg" alt="" width="650" height="465" /></p>
<p>Folding here is Alleghanian in age: that&#8217;s when the Valley &amp; Ridge province enjoyed the bulk of its deformation.</p>
<p><img class="alignnone size-full wp-image-10779" title="brallier19anno" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier19anno.jpg" alt="" width="650" height="465" /></p>
<p>Folding was accomplished partially by flexural slip &#8211; that is, each relatively stiff bedding plane slid relative to its stratigraphic neighbors above and below. This means that the bedding planes are essentially being reactivated as a kind of fault plane. And, like fault planes, they are decorated with polish and slickensides:</p>
<p><img class="alignnone size-full wp-image-10782" title="brallier05" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier05.jpg" alt="" width="650" height="867" /></p>
<p><img class="alignnone size-full wp-image-10790" title="slicks" src="http://blogs.agu.org/mountainbeltway/files/2013/04/slicks.gif" alt="" width="650" height="867" /></p>
<p>Elsewhere, the bedding planes accomplished folding by internally fracturing. Check out this chunk of graywacke from one of the bigger turbidites:</p>
<p><img class="alignnone size-full wp-image-10780" title="brallier02" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier02.jpg" alt="" width="650" height="488" /></p>
<p>You can see a series of small extensional fractures on the upper edge: this would have been the outer part of the fold.</p>
<p><img class="alignnone size-full wp-image-10781" title="brallier02anno" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier02anno.jpg" alt="" width="650" height="488" /></p>
<p>Many of the joints (fractures) at this site exhibit lovely plumose structure, that feathery fine anatomy that shows how the fracture surface originated and grew over time.</p>
<p><img class="alignnone size-full wp-image-10783" title="brallier07" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier07.jpg" alt="" width="650" height="410" /></p>
<p><img class="alignnone size-full wp-image-10784" title="brallier07anno" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier07anno.jpg" alt="" width="650" height="410" /></p>
<p>These joints are easy to find in the GigaPan above. In places, two intersecting joint sets give a lovely &#8220;sawtooth&#8221; to the edge of the beds where they crop out:</p>
<p><img class="alignnone size-full wp-image-10788" title="brallier18" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier18.jpg" alt="" width="650" height="488" /></p>
<p>Fractures, of course, are great &#8220;plumbing&#8221; for subterranean fluid flow. Here, fluids flowing through the two bed-cutting joint sets produce a beautiful cross-hatching pattern highlighted by rust:</p>
<p><img class="alignnone size-full wp-image-10785" title="brallier15" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier15.jpg" alt="" width="650" height="867" /></p>
<p>Some of the fluids were silica-rich, and deposited perfect little euhedral quartz crystals on the walls of the joint surface, transforming them from mere joints into veins.</p>
<p><img class="alignnone size-full wp-image-10786" title="brallier16" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier16.jpg" alt="" width="650" height="812" /></p>
<p><img class="alignnone size-full wp-image-10787" title="brallier17" src="http://blogs.agu.org/mountainbeltway/files/2013/04/brallier17.jpg" alt="" width="650" height="738" /></p>
<p>We spent a nice 45 minutes at the site, GigaPanning and looking around. There was a lot to see. I&#8217;d love to bring students back, but it&#8217;s a long way from NOVA.</p>
<p>Maybe some summer I&#8217;ll run a &#8220;Geology of Virginia&#8221; class that can travel around the state they way my summer Rockies field course travels around Montana. Then we could hit these outcrops that are further afield.</p>
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