A map of Skyrim with the Eastmarch highlited on the eastern side
(Image from elderscrolls.wikia.com)
Upon exploring the hot springs in the Eastmarch, I noticed that the entire area was very large and flat for the most part. I also found many geysers dotted throughout the hot springs. This large area of hot springs is a massive caldera. This would explain the formation of so many hot springs and geysers. The region is also somewhat circular and surrounded by large mountain ranges on either side. The caldera is very similar to Yellowstone.
Hot springs in the Eastmarch caldera
A large geyser in the hot springs
Another interesting thing I found near the immediate center of the caldera was a large rock formation that looked to be a rhyolite dome leftover from a volcanic eruption. The formation itself is called Bonestrewn Crest, named after the many mammoth bones strewn about the rock formation. It reminded me of the building rhyolite formation in Mt. St. Helens.
The rhyolite formation in the center of the caldera
A sky view of the Eastmarch caldera noting the position of Bonestrewn Crest in the center
One other thing I noticed while searching the landscape was this fault in the ground most likely from compression.
The fault shown here with the ground on the left about a foot higher than on the right
The people that live in this part of the Eastmarch make use of the warmer temperatures in this volcanic area to establish hunting camps where game such as sabre cats, bears, mammoth and elk are hunted. The large rhyolite formation in the center of the caldera is also a roosting spot for dragons.
-All above images except for the map are in-game screen captures done by myself.
