|Mammoth Hot Springs|
Mammoth Hot Springs--a vast area of steaming travertine terraces--are quite different from thermal areas elsewhere in Yellowstone. Hot water rising through limestone--deposited here millions of years ago by vast seas--dissolves the rock, depositing a white chalky mineral on the surface that forms ever-changing terraces that can look like ice fields.
Also at Mammoth is historic Fort Yellowstone and its grassy parade grounds. Elk come down from the hills toward sunset to graze there, challenging rangers to control onlookers.
We stayed two nights in a Mammoth Hot Springs cabin (pictured at bottom), passing through the historic Roosevelt Arch to enter the Park from the north.