Sentences with phrase «shallow rock layers»

A six - year study of seismic activity along the San Andreas Fault found that the 2004 Parkfield earthquake caused breakage and microcracking in shallow rock layers that changed the speed at which seismic waves moved through the area, making it more vulnerable to tremors for more than three years afterward.

Not exact matches

During field trips out to West Texas, he and Rice students noticed hundreds of ash layers in exposed rock that dated to the Cretaceous period when much of western North America lay beneath a shallow ocean.

Created nearly 400 million years ago on the surface of a shallow inland sea, the Marcellus Shale formed as tectonic plates pushed up the landmasses that created the Appalachian and Catskill mountain ranges and buried the ancient sea under a layer of rock almost two miles thick.

Scientists at the University of Edinburgh identified the tracks in layers of rock, which would have been at the bottom of a shallow, salt water lagoon when the prints were made.

Fill container with a shallow layer of rocks (this helps with drainage).