Geologic Points of Interest by Activity - Glacial Activity

Bridger-Teton National Forest (1)
 Fishlake National Forest (2)
 Humboldt-Toiyabe National Forest (1)
 Sawtooth National Forest (2)

Forest

Bridger-Teton

Site Name

Moraines at Fremont Lake

Directions

From Pinedale , WY take Fremont Lake Road just east of Faler's General Store. At 2.5 miles, you'll pass an overlook with interpretive signs and a great view of the lake. Continue to 3.2 miles and follow the signs.

Description

Fremont Lake is the second largest lake in Wyoming as well as one of the deepest lakes (600 feet) in the United States. Pleistocene glaciers of the Bull Lake and Pindale glacial periods carved out the valleys in this area and deposited terminal moraines that dammed the mountain waters. Fremont, New Fork, Half Moon, Boulder, and Willow Lakes all formed in such a manner. The massive glacial moraines surrounding Fremont Lake are classic examples of moraines formed by alpine glaciation.

Moraines are made of rock debris, fallen or plucked from a mountain and transported by glaciers. The piles of debris show where the terminus of the glacier paused for a while. Till is another word used to describe the sediments left by melted glaciers.

The Bull Lake Glaciation is a glacial period that began roughly 200,000 years ago and ended 130,000 years ago when a large sheets of ice began carving valleys in the Rocky Mountains. The name Bull Lake Glaciation itself is derived from the well-preserved moraines found in the vicinity of Bull Lake near the Wind River Mountains but also sent a valley glacier down Pine Creek where Fremont Lake is today. The Bull Lake Glaciation was immediately followed by a much warmer interglacial period that lasted roughly 60,000 years, preceding the advance of the Pinedale Glaciation.

The Pinedale glaciation was the last of the major ice ages to appear in the Rocky Mountains. The Pinedale lasted from approximately 30,000 to 10,000 years ago and was at its greatest extent between 23,500 and 21,000 years ago. This glaciation was somewhat distinct from the main Wisconsin glaciation as it was unrelated to the giant ice sheets and was instead composed of mountain glaciers. The Pinedale glaciers overrode the Bull Lake moraines in the Pinedale area.

Look for the characteristic U-shape valleys as well as residual glaciers that still occupy the higher peaks. Glacial features such as horns and steep-walled cirques are also present in the Wind River Mountains (Blackstone, 1988).

Image(s)

Photo of Fremont Lake with the moraines in the background - Click on the image to enlarge.
 

Forest

Fishlake

Site Name

Fish Lake and Fish Lake Basin

Directions

Head south on I-15 from Salt Lake City, UT. Take the Scipio exit (188) to US Highway 50. Travel 30 miles on Highway 50 to Salina. Travel from Salina to Sigurd on I-70 (take exit 48, which is the start of Utah Highway 24). Follow Highway 24 south to the Fish Lake turnoff (Utah Highway 25, the Fish Lake Scenic Byway).

Travel north on I-15 from Southern Utah or Cedar City, UT. Take exit 95, travel southeast on Utah Highway 20 for 21 miles. Then take US 89 north to Kingston. At Kingston, take US Highway 62 east and then north at Otter Creek Reservoir to its junction with Utah Highway 24. Head south on Highway 24 to the Fish Lake turnoff (Utah Highway 25, the Fish Lake Scenic Byway). Follow Utah Highway 25 northeast 13 miles to the end of the byway. Here you will enter the Fishlake National Forest about three miles along the route.

Description

Much of the underlying rock of Fish Lake Basin is composed of basalts that flowed from fissures then cooled. The basin itself formed when one block dropped down between two faults on either side. On the southeast side of the lake lie the slopes of Mytoge Mountain and on the northwest side, Fish Lake Hightop Mountain.

The fault blocking occurred at different times and at different places along a10 mile stretch. The ends of the basin have not settled concurrently as recent evidence suggests that the lake once drained to the south rather than its current route to the north at Lake Creek.

Glacial activity also played a role in carving canyons and depositing moraines in Fish Lake Basin. Well-noted evidence of this activity is at Pelican Canyon (Godfrey.)

Image(s)

Photo of the Fish Lake Basin - Click the thumbnail to enlarge.
 

Forest

Fishlake

Site Name

Terminal Moraine on Pelican Canyon

Directions

Head south on I-15 from Salt Lake City, UT. Take the Scipio exit (188) to US Highway 50. Travel 30 miles on Highway 50 to Salina. Travel from Salina to Sigurd on I-70 (take exit 48, which is the start of Utah Highway 24). Follow Highway 24 south to the Fish Lake turnoff (Utah Highway 25, the Fish Lake Scenic Byway). Pelican Canyon is located at the north end of Fish Lake. A road diverges from Fishlake Scenic Byway to Pelican Overlook.

Description

Pelican Canyon was carved out by glaciers and Pelican Overlook sits atop the moraines left from that activity. Melting glaciers washed sediment out into the lake in a fan-shaped deposit nearly dividing the Fish Lake in two. A narrow straight remains between Widgeon Bay and the main part of Fish Lake at Pelican Point. 

Image(s)

 
 

Forest

Humboldt-Toiyabe

Site Name

Lamoille Canyon

Directions

Twenty miles east of Elko, Nevada.

Description

The Ruby Mountains of northeastern Nevada are among the state’s wettest and most lush mountain ranges. Lamoille Canyon, in the heart of the range, offers some of the most spectacular views found in the Rubies. Sometimes referred to as the "Yosemite of Nevada," the canyon was heavily carved by glacial activity. A four-stop self guided auto tour with geology interpretive exhibits leads visitors past meadows full of wildflowers, abundant wildlife, waterfalls, and avalanche chutes. The Lamoille Canyon Road winds around the base of 11,249-foot Ruby Dome and climbs through the glacier-carved canyon. At the end of the 13.5-mile paved road, at the 8,800-foot level, is a parking area and trailheads, for long and short hikes.

Image(s)

Photo of Lamoille Canyon - Click on the image to enlarge.
 

Forest

Sawtooth

Site Name

Bethine and Frank Church (Galena) Overlook

Directions

Take Highway 75 (Sawtooth Scenic Byway), near Ketchum , ID , head north until you come to the overlook. Drive south on Highway 75 from Stanley , ID.

Description

This overlook offers panoramic views of the Sawtooth Mountains. It is due for reconstruction in the fall of 2007, but visitors can still see breathtaking views.

The Sawtooth Mountains are mostly composed of batholiths--the pink 44 million year old Sawtooth Batholith and the gray 70 to 90 million year old Idaho and Atlanta Batholiths.

Intense glaciation as recent at 14,000 years ago carved the rough Sawtooth Range and left glacial moraines now forested along the base of these mountains. There are also many lakes nestled within these moraines. The sawtooth appearance of the mountains is due to the pervasive vertical fracturing of the granite.

Image(s)

Photo from the Galena Overlook - Click on the thumbnail to enlarge. View of the Sawooth Mountains - Click on the thumbnail to enlarge.
 

Forest

Sawtooth

Site Name

Redfish Lake

Directions

Redfish Lake Lodge is located 60 miles north of Sun Valley and 8 miles south of Stanley just off Highway 75.

Description

Redfish Lake is a glacial lake that occupies a U-shaped, glacially-carved valley. The water is contained on the sides by lateral moraines and on the north end near the lodge by a terminal moraine. Redfish Lake lies on a platform of Pleistocene glacial sediment, rimmed by Pinedale-age moraines and flanked to northwest and southeast by Bull Lake-age moraines and outwash terraces. The prominent morainal ridges high above the lake to the northwest and southeast are similar to the large, outermost moraines marking major drainages farther south on the Sawtooth front, likely constructed during early or middle Wisconsin time. Due west of this location are similar moraines, merging with the large Redfish moraines but constructed by glaciers descending the Fishhook Creek drainage. Smaller, younger moraines mark the shores of the lake and areas upvalley, but, surprisingly, remain unstudied. Redfish Lake Moraine Research Natural Area encompasses a section of the large lateral moraine on the east side of Redfish Lake.

Image(s)

Photo of Redfish Lake - Click on the thumbnail to enlarge.