Day 3: Paradox Valley. Go to More Photos for Day 3?
Overview of this Site
The picture above is not from the Paradox Valley, but it is from the Paradox
Basin. Pennsylvanian rocks in the Paradox Basin act as the source as well
as the reservoir for oil and gas. It is difficult to look at the Pennsylvanian
rocks of the Paradox Basin at the surface of the Earth because in most
places they are buried. Cores taken by oil companies provide some rock,
and electric logs give information about areas where no core is available.
A prominent characteristic of the Pennsylvanian rocks is their cyclicity.
Salt, carbonates, and black shales alternate again and again. Some geologists
think that these cycles reflect changes in sea level and/or changes in
climate. Because the southern continents (Gondwana) were glaciated during
the Pennsylvanian, repeated formation and melting of glaciers could be
a mechanism that produced the Pennsylvanian cycles.
In the Paradox Valley, collapse of a salt-cored anticline resulted in
formation of a valley that trends at about 90 degrees to the river that
travels through the valley (hence the Paradox). In the valley, remains
of the Pennsylvanian salt can be seen.