*** This EarthCache is located in Gros Morne National Park. As such all visitors at the site are required to purchase a Park Permit before they enter the park to complete the EarthCache. ***
BEFORE you may log and claim this EarthCache as a find, you must first send a message or email me through my profile your answers to the following questions. Do NOT put answers in your log postings! (Answers to the questions can be found by reading the EarthCache description, reading the interpretive sign at the EarthCache coordinates, and making observations.)
- According to the information sign at the posted coordinates, how many years ago was Burridge's Gulch created?
- What evidence is there remaining in the valley of the glacier that once flowed where you are standing?
- Estimate the height of the hanging valley.
- Optionally post a picture of yourself and/or your GPSr with the valley in the background or at the nearby waterfall.
*** All sincere efforts to answer the questions and complete the tasks will be accepted. ***
Laurentide Ice Sheet
During the last ice age, the Laurentide Ice Sheet covered most of Canada and a large part of the northern United States. These advancing and retreating glaciers had a tremendous impact on the landscape.
Scouring the Landscape
As glaciers advance across a landscape, they pick up whatever is in their path from grains of sands to large boulders. These rocks are frozen to the glacier and taken along with it. This process is known as plucking. Under the enormous weight of the glacier, the rocks and sediment carried by the glacier alters the landscape through the action of scouring (rubbing the surface with something abrasive, such as rock sediment), eroding and carving valleys in their path.
U-shaped Valleys
U-shaped valleys are one of the telling characteristics of a glacier (mountain glaciers in particular) as they are formed by the process of glaciation. They have a characteristic U-shape (hence their name) with steep sides and a flat or rounded valley bottom. The valleys are often littered with boulders, called erratics, once the glacier recedes.
Hanging Valleys
The size (depth) of the valley largely depends on the size of the glacier. The more weight a glacier has the larger a valley that it erodes. A hanging valley is formed when a smaller tributary glacier flows into a larger main glacier. The main glacier erodes a large U-shaped valley while the tributary glacier carves a smaller (more shallow) U-shaped valley that intersects with the main glacier. Because the surface of both the main and tributary glaciers began at the same elevation, the smaller more shallow valley appears to "hang" above the main valley.
Please be respectful of the fragile environment you are walking through. There is no need to go off the trail anywhere to complete this EarthCache.
Sources: Wikipedia, How to recognize a Hanging Valley interpretive sign.