Tuesday, March 29, 2011

Details from the No Thoroughfare Trail in Colorado National Monument Part 1

One of the few hikes I was able to undertake over spring break was back to No Thoroughfare Canyon.  While there was still some ice back up at the first waterfall, most of the trail was fairly dry this time. The ice from the creek had melted as well, so for the first time I was able to see some of the small (and by small I mean maybe a couple feet) canyons through which the creek had started to erode.
Precambrian rocks cut by the creek.

 You may remember this little guy from the last post I had on this trail.
This time with scale!

Here it is in relation to the boulder, hiding in the corner.
I was pretty fascinated by it the first time around, so it was mostly my goal this hike to find him again.  Turns out, it wasn't as far up the trail as I had remembered. It's on a boulder just past the first pool the creek forms, maybe a mile or so in from the trailhead.  I took a few more pictures to bring in to my Geology teacher and continued up the trail.

Well, I found quite a few more of these little inclusions in the Precambrian rocks.

Relatively large inclusion with chapstick for scale because I forgot the swiss army knife I usually carry.

Partially eroded inclusion. you can see the deep red by the rusting of iron rich minerals.
Almost fully eroded inclusion.
After seeing several of these along the hike, I had come to the hypothesis that these were older, possibly sedimentary rocks (due to the fact that they are more easily eroded than the surrounding rock) from before the igneous and metamorphic Precambrian rocks formed.  I brought this theory, along with a picture to my geology teacher last week, and he said there were indeed some sandstones and limestones (both sedimentary rocks) that had been included in the Precambrians. 

Huzzah! I'm learning!

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