This week?s Friday Field Photo is from an area near and dear to me ? the mountains and desert of west Texas. I did my master?s thesis work in this area in the early 2000s and it?s beautiful country. Exposed in the Delaware Mountains, just south of Guadalupe Mountains National Park, is a 250 million year old deep-sea sedimentary system called the Brushy Canyon Formation.
What?s great about this outcrop is the ability to reconstruct an ancient seascape in three dimensions. The mountain range is dissected by numerous normal faults that expose the same stratigraphic level across multiple cliff-and-canyon exposures. The photo above is a typical example of the exposures. If you look carefully you can see a zone of lighter-colored and thicker-bedded sandstone along a cliff face in the left-center part of the photo. This localized zone of coarser-grained sediment is the fill of a submarine channel system that traversed the floor of a deep marine basin in this area during the Permian.
Now the coolest part of all this how you can map these submarine channel features from cliff face to cliff face. The same channel-fill feature is exposed again on the cliff in the foreground. The arrows on the photo below point this out probably more clearly than my explanation.
When you combine this type of mapping with sedimentary features that indicate the direction of flow (paleocurrent measurements) you can then reconstruct an ancient depositional landscape at very high resolution.
Happy Friday!
Source: http://www.wired.com/wiredscience/2011/06/friday-field-photo-146-deep-sea-landscapes-in-the-desert/
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