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.
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.
Return to
Geology of Utah's National Parks Home Page
Return to
Introduction to Photos Page