TEXTURAL ANALYSIS OF THE ASHTABULA, HIRAM, AND LAVERY GLACIAL TILL IN ERIE COUNTY, PENNSYLVANIA

Three end moraines are preserved in Erie County, Pennsylvania and were formed by three pauses during the retreat of the Laurentide Ice Sheet in the late Pleistocene. These end moraines are sub parallel to the present shoreline of Lake Erie. The youngest is the Ashtabula end moraine located farthest to the north, followed by the Defiance end moraine, and the Lavery end moraine located furthest to the south is the oldest. Each end moraine is composed of different glacial till and inceptisols that have formed in the upper 25.4-12.7 cm level. Previous studies of the till in northwestern Pennsylvania were able to separate the deposits into various stratigraphic units on the basis of texture. However these studies only analyzed the texture of the till matrix and ignored particles larger than sand (Shepps et al. 1959).

The purpose of this study is to expand upon past research by conducting a textural analysis of the different tills in each end moraine in order to gain a more accurate understanding the till’s texture. This will be accomplished by using sieves to determine the percentage of coarse grained particles (cobble-sand) in addition to using a Beckman Coulter Counter to determine the percentage of fine grained particles (sand-clay). In addition the use of the Beckman Coulter Counter will allow for more detailed and accurate analysis of the till matrix, which includes a determination of the mean grain size.

Samples were collected below the topsoil with the use of an auger and observations in the field have noted that all samples contain enough cobble sized particles to result in an overall coarser texture. Once textural analysis is complete the textures of each till will be compared to one another in order to see if texture can still be used in order to differentiate between the glacial sediment in Erie County. Moreover this study will also address whether or not grain size changes as a function of depth.