During the past week I have spent time practicing field methods that will be used during the spring break trip to Lee’s Ferry. I hope to use some of the mapping techniques on our individual project if applicable.
My main focus this week was looking at the properties of bentonite clay to further understand its significance. By searching quickly it was interesting to find that bentonite is used largely for medicinal purposes; including digestive symptoms, morning sickness, and used on the skin ( Medicinal). This discovery was not to surprising since kaolinite is used in many health products as well. However, kaolinite and bentonite clays are in two different groups. The bentonite clay is a smectite and is specifically referred to an impure form of montmorillinite (Clay). Smectite clays are highly expandable and tend to form in the tropical regions where clays form with abundant aluminium (laterite soils), but can also be found in cool and dry regions (Book). With the abundant information on the crystal structure of bentonite and the location it is typically found, I am going to look at the paleoclimate of the region we are looking at to determine what the conditions were like when the ash was deposited. It is still a little confusing how the volcanic ash is a clay, but it is starting to become more clear.
The paleoclimate data should be easy to find. The ash layers were mainly deposited in periodic episodes during the Mesoizoic (Age). I found an article by the USGS that describes the depositional and climatic settings that will help me continue with this subject.