National Geographic posted a cool time-lapse video showing the growth of the lava dome on Mt. St. Helens. The volcano is still active and a recent flurry of earthquakes suggests that magma is still moving beneath the volcano.
Apparently defining the source of a river is really complicated. This article from the BBC explains why defining the source of the Amazon, Nile, and Thames Rivers is still a subject of debate.
The U.S. east coast is not supposed to be subject to intense earthquakes. Most earthquakes occur along active plate boundaries. The U.S. east coast is located on a passive margin.
However, on August 23, 2011 a magnitude 5.8 earthquake occurred in Mineral, Virginia, about 70 miles southwest of Washington, D.C.
Berk Biryol is a geologist at the University of North Carolina at Chapel Hill and is the lead author on a recent article in the Journal of Geophysical Research: Solid Earth which discusses this topic.
Biryol and his co-authors suggest that the upper mantle is peeling off of the crust and sinking into the Earth. This causes the Earth's crust to thin and weaken, thus making it prone to earthquakes.
The image above was taken by astronaut Tim Peake, from the International Space Station. It shows Tenerife, the largest of the Canary Islands. You can very clearly see all of its volcanic features from space. Wired Magazine published an excellent geologic breakdown of what is observed in this image. Click the link below to see the full story.