To log this cache please visit the location and email me the answer to the following questions. Please send your answers and logs at about the same time, you could have your log deleted if I cant track down the matching log.
- Who are you submitting answers for (if you are submitting for a group)
- Does all the sandstone in the area appear to be cross bedded or not?
- At the North base of the arch there are a number of cross bedded outcrops, are the foreset layers of similar thickness within them or varied?
- How does the cross bedding at the north base of the arch compare with the sandstone around the area.
- To try and stop cheaters please post a photo of yourself, foot, paper with your caching name, or GPS.
Sand Deposits
Sand is deposited to form sandstone in two ways. First is by river deposits. The rivers can flow into oceans or flood plains and deposit the sand layer by layer, building it up over time to form a deep layer that forms into sandstone.
The other way is by dunes. Sand blowing and moving across the landscape and pushing that material into great sheets that eventually get hard, and that will be covered by another dune, and by another. This will form patters in the sandstone as these frozen dunes solidify.
These sedement layers that are blown over the dune are referred to as a Foreset layer. As they are deposited based on varying winds, water flows, etc. They will have heavy grains to lighter grains. This helps determine the layers, and also the different rates they the layers erode, and sometimes the coloring of the layers.
What is learned from them
By looking at the direction that they are laid down into, you can learn a lot from the cross bedding. It lets you know the direction of wind or water flow. This can be very difficult, as you have to determine the direction. Remember quite often you are looking at a cross section of a dune. The deposits here among the find allow scientists to walk around the fin and help determine the windward side and direction of the wind.
Types of Cross Bedding
There are two primary types of cross bedding.
Tabular cross bedding is usually even angular layers that are from the movement of large dunes or other deposits. . The layers can be a few millimeters thick to a meter or more. They can be caused by Dunes, river deltas, or glaciers.
Trough cross beds are curved in their deposits. They would be from much smaller flows and deposits. It is far easier to determine flow direction. Usually the smaller features are deposited, then partially eroded from water or wind, before another deposit is made.
Other important notes
Permission given by the National Park Service
Report any Vandalism to Park Rangers
Remember it is hot in the summer and plan for it. Summer temps can hit 100° F (40°). That will not be the temperature on the rocks. It will be higher. Be prepared with a hat, sunscreen, and lots and lots of water.