Towers of the Black Hills...Please let me know if you have more lookouts in the area I can add... (fire, geological, or other).
Spread throughout the Black Hills National Forest of South Dakota and Wyoming are quite a few towers. Some are extant and manned during the summer. Some are extant and near abandoned. Others have been removed, others have been burned down or blown down. This page intends to collect them in one location for historical, informational, and interesting purposes.
THE BLACK HILLS
The Black Hills region spans from the western 1/4 of South Dakota and runs generally NW into Wyoming. The area was lifted by the intrusion of a huge area of granite which forms most of what people visualize when they hear reference to the Black Hills, and makes for splendid hard rocks - basalt, granite, and pegmatite. This is the rock in which the Rushmore Monument and Crazy Horse memorial are carved. On the west edge, the end of the Great Inland Sea overlaid the seafloor, so there is a rather large area of limestone overlying the sandstone. As this was lifted, so was the edge of the sandstone. This is most visible in areas like Redfern Canyon in South Dakota.
There is a better detailed page on the geology of the Black Hills on Wikipedia's Black Hills page
There is also an interesting page on fire lookouts in South Dakota here
is the same page for the ones in Wyoming.
The reasons behind the towers...
Fire Lookout Towers
So the blatantly obvious reason is to spot fires, usually started from lightning strikes, but sometimes from people's carelessness or, worse, arson.
Seth Bullock/Scruton Mountain
Elk Mountains High Point/Elk Mountain lookout
Little Devils Tower
Some of the documentation for the lookouts is rather poor.
Mount Theodore Roosevelt
No longer extant towers, or ones that never existed...
Crows Nest Peak
The Towers and their peaks
The peaks almost always sit on top of a peak (or very near the top) of a lot of peaks. Most have a decent amount of prominence, others simply have a great view due to elevation.
External links for history buffs
The National Historic Lookout Register
has an interesting site on the fire lookout towers of not only the Black Hills, but all of the US.