Mud volcano.

Bibliographic Details
Format:	Book
Language:	English
Published:	Yellowstone National Park, Wyoming : Yellowstone Association in cooperation with the National Park Service, [1995]
Edition:	Revised April 1995.
Subjects:	Mud volcanoes > Yellowstone National Park > Guidebooks. Nature trails > Yellowstone National Park > Guidebooks.

Cushing: Stonestreet (Does not check out)