Glaciers and Glacial Landforms

Glaciers carve a set of distinctive, steep-walled, flat-bottomed valleys. U-shaped valleys, fjords, and hanging valleys are examples of the kinds of valleys glaciers can erode.

Cirques are bowl-shaped, amphitheater-like depressions that glaciers carve into mountains and valley sidewallsat high elevations.

Nunataks, arêtes, and horns are the result of glacial erosion in areas where multiple glaciers flow in multiple directions. When the ice is present, they form stark, rocky outcrops above it, adding to the beauty of these harsh landscapes. Once the ice retreats, these uniquely-shaped features provide clear evidence of past glacier flow

Lateral and medial moraines consist of glacially-transported rock and debris. They form on the sides of glaciers (lateral moraines) or at the boundary between two tributary glaciers (medial moraines). Either way, they often mark the edges of an ice body

Terminal and recessional moraines mark the farthest reaches of a glacier—its terminus—at a given point in time. They are usually built from rocks and debris that are transported to the glacier toe in the ice and melt out there

The sediments produced through glacial grinding are very distinctive. Glacial till contains sediments of every size, from tiny particles smaller than a grain of sand to large boulders, all jumbled together. Glacial flour is that smallest size of sediment (much smaller than sand) and is responsible for the milky, colored water in the rivers, streams, and lakes that are fed by glaciers.

Glaciers can pick up chunks of rocks and transport them over long distances. When they trop these rocks, they are often far from their origin—the outcrop or bedrock from which they were plucked. These rocks are known as glacial erratics.

As glaciers flow over land, they incorporate pieces of rock and sediment into the ice. These inclusions make the glacier sole (the bottom of the glacier) into a kind of coarse sandpaper that is capable of scratching bedrock. Over time, the glacier moves over rock and sediment, leaving striations or striae, on the rock surfaces that can reveal the direction that the glacier was flowing.

Paternoster lakes occur in a series down a formerly glaciated valley in small basins scooped out by the glacier as it retreated.

As a glacier recedes, sediment is washed out from the glacier and deposited in a flat area below, forming an outwash plain. Depressions, known as kettles, often pockmark these outwash plains and other areas with glacial deposits.

There are many geological features at Acadia that are noticeable and identifiable. While you are out in the park, keep an eye open to discover ways the rock shapes our experience.

Permafrost in Alaska and mountain permafrost in the contiguous states forms the physical foundation on which terrestrial ecosystems and infrastructure rest. Factors that influence permafrost can include: climate, physical terrain, hydrology, vegetation, geology, soil, and disturbances. The geologic monitoring manual provides methods to establish the status and trends of geologic resources within dynamic ecosystems.

The dynamic nature of glaciers strongly influences the hydrologic, geologic, and ecological systems in the environments in which they exist. Glacier change is important because it provides basic data for understanding and assessing past, current, and possible future conditions of the local, regional, and global environment. The geologic monitoring manual provides methods to establish the status and trends of geologic resources within dynamic ecosystems.