A simple Earth Cache, just meant to get you outdoors to enjoy a great hike. A very similar cache to "Another Groovy Earthcache" GC6VN4F
Should be a very easy cache to get, but the fun for this one is in the hike to get here and enjoying the views the area has to offer.
Glacial Grooves or "Striation's" are straight parallel scratches or gouges cut into bedrock by glacial abrasion. These grooves were formed by the coarse gravel and boulders being dragged along underneath the retreating glacier. This resulted in a scrapping or gouging of the surface of the bedrock, thus creating the glacial grooves. It is believed that these glacial grooves indicate the direction of flow of the retreating glacial ice. Glacial grooves are found in many parts of the world. They can vary in size, from a few inches deep to a few feet in depth.
Some reasons for Glacial Striation are as follows:
- The amount of rock debris in the basal surface of the ice. If there is no rock in the basal surface of the ice there will be no abrasion, but if there is too much rock in the basal surface of the ice the motion of the glacier will be affected, thus affecting abrasion rates.
- As the bedrock is being worn away the abrading fragments within the glacier are also being worn. Similarly to sandpaper being worn away with use. A continued supply of abrading fragments is required to uphold a similar level of abrasion.
- The fragments must be harder than the bedrock. Quartz fragments will abrade shale but shale fragments will not abrade a quartz rich bedrock.
- A constant flow of melt water between the basal surface and the bedrock speeds abrasion. The meltwater constantly rinses away the rock flour allowing the coarser fragments to abrade bedrock.
- Speed of the glacier. The faster the glacier moves, the faster the bedrock will be eroded.
- Thickness of the ice. Thicker ice causes more downward force and increased pressure between the abrading fragments and the bedrock. There is a limit to how much ice will enhance abrasion. If the friction force between fragments and bedrock is too great the ice will flow around the fragments.
- Basal meltwater under high pressure. If the meltwater is under sufficiently high pressure it will cause the ice to effectively buoy up and decrease the normal force of the ice on the bedrock. Another result of this is that the velocity of the glacier is increased.
- Shape of the fragments. Larger more angular fragments will scratch and scour more effectively than small and round fragments will.
To claim this cache just answer a few very simple questions.
1. What is the depth of the glacial groove at the posted coordinates (next to the trail sign)?
2. What direction does it follow?
3. From the above information, how do you think these groves were formed?
4. Post a picture with your GPS at the showing some of the beautiful scenery of the area in the background.(Optional under new rules)
Please Email me the answers, do not post them in your log. Any answers posted will be deleted, along with the log entry.