We just spent four days in Yellowstone, and had a great time seeing the sights and marveling at the geology. Everyone wants to know if we saw bison. Yes!! We saw them every day! This was a huge herd … more than 100 animals … and we couldn't resist a picture out the car window to catch this iconic shot. Yellowstone is famous for its hot pools. This was at the Paintpots. What an amazing color! And of course there are geysers everywhere. We didn't stop at Old Faithful because the parking lot was a mob scene, but we saw plenty of water shooting up in the air, nonetheless! Another hot pool and geyser in the south loop, with beautiful mountains as a backdrop. Artist's Point is a must-see for anyone who loves photography or painting. Another iconic Yellowstone view! Mammoth Hot Springs, near the north entrance. These limestone formations are building up year after year. The hot water dissolves minerals underground and carries them up to the surface. The minerals fall out of solution as the water cools, forming these fascinating steps. Another view from the other side of the lower hot springs. The upper hot springs had some wonderful scenery as well. The limestone is so white, it's blinding! Looking down from the upper hot springs rim you can see the small gathering of buildings near the north entrance. The red-roofed buildings on the right are the original Fort Yellowstone complex, constructed between 1886 and 1913. The white and gray buildings on the left are park service buildings, hotels, and all the things necessary to serve the tourists who come here in droves every year.