Jill L.

P and S waves are seismic waves that travel through the earth, as opposed to the surface waves which travel above the earth. P waves, also known as Primary waves travel in compression. S waves,... more

I've seen models in astronomy that show how the Earth-Moon system must have come together after a collision. However, I have not heard whether there is any actual physical evidence on Earth that... more

What is the age of the lithosphere that is subducting beneath the Pacific Northwest?