Glacier NP, Flathead Valley Geology

Glacier National Park currently has 27 modern glaciers, but its name comes from the monstrous glaciers that carved out its landscape tens of thousands of years ago.

A Geology Lesson

Glaciers form when snowfall is greater than the summer’s melting snow. The snow on top pushes down on the lower layers and compacts them. The ice near the bottom becomes flexible and allows the ice to move, and it often does – downhill. When it starts to move it’s called a glacier.

Glacier National Park currently contains 27 glaciers, however it’s the gigantic glaciers from tens of thousands of years ago for which the park is named.

Some of the results of glaciers forming from these earlier times are easily seen within Glacier National Park. The features to look for are:

Mountains: these Rocky Mountains were formed by the collision of Earth’s plates, which pushed rocks up into the gigantic ridge of mountains you see today.

Horns: as glaciers move along all sides of a mountain at the same time, peaks called horns are formed.

Cirques: these are large bowls that are carved out by a glacier’s movement, which commonly fill with water.

Aretés: these are thin ridges that come about when two glaciers move along the opposite sides of the same wall.

Hanging valleys: these small valleys are near the tops of the mountains and made by small tributary glaciers.

Moraines: moraines are the deposit of rocks and debris from a glacier that has carried this debris along and left it in piles as it melted.

Hikes and Attractions

• Chief Mountain
  Chief Mountain is located on the eastern border of Glacier Park on the Blackfoot Indian Reservation. There are various trails leading to the top and the hike is classed as strenuous (Class 2 and 3) but is a Class 4 along the summit ridge. The views are stupendous! This shows how the rock formations of the Rocky Mountain landscape virtually leaped out of the prairies.
• Mt. Reynolds at Logan Pass
  The Highline Trail takes you along the west side of the Continental Divide and through the Garden Wall (see below). Mt. Reynolds is an example of a horn or steep mountain peak.
• Lakes to Visit
  These cirques are excellent examples of glacier-carved bowls where water collects. Avalanche Lake is named for the number of avalanches that fall down from the surrounding mountains, particularly in May. Later, these avalanches turn into waterfalls, making some incredible photo opportunities. You can hike to the lake as early as May from the trailhead off Going-to-the-Sun Road. The other lakes (Iceberg Lake and Gunsight Lake) are accessible by trails and invite you to take to the backcountry to experience the best of Glacier National Park.
• The Garden Wall
  Here you have an example of an arête (a French word meaning “fish bone”). The Garden Wall separates the Lake McDonald Valley from Many Glacier Valley. Wildflowers bloom abundantly here and that is why the name.
• Mount Oberlin
  A hanging valley on this mountain offers a waterfalls cascading from its depths. Mount Oberlin is probably one of the two easiest climbs in the park and worth a visit.

Learn More

To get more information about the geology of Glacier National Park, it’s easy to find out all you need to know by touring the Visitor Centers.

Logan Pass Visitor Center has an alpine ecology exhibit, fascinating in its detail of life above the tree line. This center is open in the summer from mid-June to mid-September and is located on the summit of Going-to-the-Sun Road.

The Apgar Visitor Center (located in Apgar Village) has relief maps of the park and much information about the geologic history of Glacier National Park. St. Mary Visitor Center (at the East Entrance) provides the same type of education, as well as an introductory slide program. Both open in mid-May and Apgar stay open to mid-December and Saint Mary is open until mid-October.

The Many Glacier Ranger Station has hiking and trail information and general information about Glacier Park. You can also stop by the Wayside exhibits as you travel the park roads and see highlights of special features.