Yellowstone

Old Faithful

Yellowstone is a very diverse park with elevations ranging from the Continental Divide at 8,392 ft to 7,000 feet of the Old Faithful Basin.  The forests are full of quaking aspen and lodge pole pine.  Much of Yellowstone was burned in 1987 and you can still see signs of it.  Running through the park is the Snake River and numerous lakes with Yellowstone Lake being the largest.  There are also numerous Falls.
We decided to spend the majority of our time at the Park visiting the thermal sites beginning with Old Faithful it erupts about every 2 hours and we only had a wait of about 20 minutes.  From there we did a 2 1/2 mile geyser walk around the numerous geysers in the basin.  A Ranger at Old Faithful said that this basin is about a mile across and is the caldera of an underground volcano.
The walk was amazing, we couldn't believe how close the boardwalk took you to the geysers, and what a treat they were to watch, some bubbling, some spewing and noisy!
The next time we went we visited the Black Sand Basin, Upper Geyser Basin, Biscuit Basin, Midway Geyser Basin and Lower Geyser Basin.  Each had walkways around them and were absolutely incredible.  Walking at 7,000 to 8,000 feet can really take it out of you and we exhausted ourselves each day.
I'll let the pictures do some of the talking for me.

One of the Geysers at Old Faithful Basin

One of the Pools at Black Sand Basin

Sapphire Basin at Midway Geyser Basin

One of the Pools at Biscuit Basin

Cliff Geyser at Black Sand Basin

Before leaving on our trip I ordered a kid's book from Amazon entitled "Who Pooped in the Park" a guide to tracks and scat that you'll see in Yellowstone.  We used it and took some pictures of our discoveries.  

We're Pretty Sure These Are Bison Prints

Mac Thinks This is Elk Scat