Paleowind Direction and the Regional Pattern of Grain Size and Atterberg Limits of Loess in Adams and Lincoln Counties, WA

Abstract

Loess is a fine-grained floury material carried by wind. The properties of loess are important for infrastructure, agriculture, and construction planning in areas where it is abundant. Eastern Washington is one such location where loess hills dominate the landscape. Past studies have established the geologic origins of loess in Eastern Washington on a broad regional scale. These studies established that paleowinds carried the loess Northeast and that gran size decreases downwind. Naturally, I set out to ask if the paleowind direction and subsequent decrease in grain size can be detected over a smaller two county area. To answer this, I collected 27 samples of loess in Adams and Lincoln counties to determine its index properties and look for regional patterns in grain size. I analyzed grain size, moisture content, and Atterberg limits. Then I evaluated the results in a geographic information system. I found that paleowind influence can be found in the grain size and properties of the loess within Adams and Lincoln counties. The results of my study provide insight into the general characteristics of loess index properties in parts of Eastern Washington and confirm the results from previous work.