Background
All of the uplifting of the rocks that you see on the mountain side
is the direct result of orogenic or mountain building activity that
uplifted these rocks as well as rocks in the Central Basin
Platform, a major geological province in the region. Associated
with the tilting of the rocks is erosion. Where rocks have been
eroded away is called an unconformity.
There are four types of unconformities in nature: a disconformity,
a nonconformity, a paraconfomity, and an angular unconformity. A
disconformity is where sedimentary rock lays on top of sedimentary
rock that has been eroded. A nonconformity is where sedimentary
rock lays on top of either an igneous or metamorphic rock that has
been eroded. An angular unconformity is where beds have been
tilted, eroded, and flat-lying rocks have been deposited on top of
it. A paraconformity is where flat lying beds are eroded and
covered by flat-lying beds but can only be recognized by the gap in
the rock record.
This area is very important because geologists are able to examine
the rocks and folds and determine why they formed in the way they
did and how this area has developed into what you see today. This
area is also associated with a large amount of oil production and
provides a snapshot image of many of the fields in the Permian
Basin allowing geologists to predict better where the oil occurs.
This is the only place where this occurs at the surface. The rocks
you are looking at are known as the Hazel Formation and Van Horn
Formation and were deposited 550-490 million years ago in the
ocean.
Tasks:
Go to the posted coordinates and answer the following
questions:
1. Are the rocks on the mountainside flat-lying or are they tilted?
To determine this follow the linear features until they meet the
rocks at the very top of the mountain. (It may help to have
binoculars or a zooming in camera for this)
2. If they are tilted, what angle are they laying at?
To determine this either bring a protractor to estimate the angle
or take a picture and use a protractor at home.
3. Referring to the descriptions of the above paragraphs and your
answer to Question 1, what type of unconformity is present in these
rocks?
4. Include an optional picture with you in it at these
coordinates.
References:
Wicander, R., and Monroe, J. S., 2000. Historical Geology:
Evolution of Earth and Life Through Time 3rd Edition. Van Der
Pluijm, B. A., and Marshak S., 2004. Earth Structure 2nd Edition.
http://sepmstrata.org/terminology/unconformity.html
