glaciers of Yellowstone questions?

1. There are no existing glaciers in Yellowstone.

2. Possibly during the Little Ice Age, which climaxed between 100 and 300 years ago. But more likely, not since the Last Glacial Maximum approximately 10,000 years ago.

3. Erosion:

The glaciers scour their beds as they flow downslope because they entrain rock debris into the ice of their undersides. The entrained rock debris acts like sandpaper on the ground surface underneath the glacier. Also, glaciers can pluck large pieces of fracured bedrock from their beds. Also, when glaciers scour out wide U-shaped valleys by the processes mentioned above, they tend to undercut and destabilize the valley walls, which causes landslides on the valley walls that deposit debris onto the top of the glacier. Finally, glaciers in temperate climates have subglacial water that flows like streams underneath the glacier. These streams can also contribute to erosion of the glacier's bed.

Depostion:

Glaciers entrain rock and dirt debris within their ice, mostly on their undersides where they can easily pick up debris from their beds. This material is call basal sediment or debris. Also, as mentioned above, landslides can deposit debris on top of a glacier. This is called supraglacial debris. Some of this debris may fall into ice crevasses in the glacier ice, which later close shut with the debris trapped inside. This is called englacial debris. When the glacier ice with entrained debris flows to the glacier's zone of ablation (melting), the ice melts and drops the debris and forms depositional features like moraines. Other depositional landforms that are created by glaciers are eskers (which form from subglacial meltwater), drumlins, flutes, and rogen moraines.

1. Today, only small remnant glaciers are present ..., mostly concentrated in the Beartooth and Wind River Mountains. (fromhttp://pubs.usgs.gov/wri/wri984269/geology.html)

But,

Although some snowfields exist year-round in the park, there are presently no glaciers in Yellowstone. A few glaciers can still be found in the Teton and Wind River ranges. (http://www.nps.gov/yell/planyourvisit/upload/Yell2...

2. The region’s most recent period of glaciation began about 50,000 years ago in the high mountains of the Absaroka Beartooth Wilderness, northeast of Yellowstone. With time, vast sheets of ice, thousands of feet thick, flowed from the mountains to converge over Yellowstone Lake, covering the Yellowstone Plateau and virtually all of the park and surrounding area. While thermal basins continued to seethe beneath the ice, this land of fire and brimstone was in a deep freeze for thousands of years. At the peak of this glacial era, roughly 25,000 years ago, prominent peaks like Mount Sheridan lay hidden underneath this icy blanket, while the tip of Mount Washburn and the thin ridgeline of the Absaroka Mountains barely peeked above this unrelenting sea of ice.(from http://www.nps.gov/archive/yell/pphtml/subnaturalf...

Glacier ice built up to as much as 3,000 feet thick (over the Lake Basin) within the park. Only the west edge of the park and the highest ridges escaped being glaciated. (http://www.nps.gov/yell/planyourvisit/upload/Yell2...

3. This is a fieldtrip guide to the Greate Yellowstone area

http://www.pdfdownload.org/pdf2html/pdf2html.php?u...

The glaciers are long gone.

I ahve been to both, and I like Glacier better ,it is more senic,more rugged and less crowded.