MAPPING GLACIAL FEATURES USING STATIGRAPHIC FIELD OBSERVATIONS AND GIS

Past textural and geomorphic interpretations of glacial features in the Birmingham Quadrangle do not correspond well with the observed stratigraphy of those glacial features. To study these differences, the observed stratigraphy data was mapped as points on a Geographic Information System (GIS), and then displayed on Digital Elevation Model (DEM) data to gain a greater understanding of the subsurface structure and the surface features.

The mapping revealed a hard packed massive clay layer that closely follows the surface elevation, and is covered by a surface layer of till. A variety of contacts and layers exist between the clay and till layer which include: direct contact, armored contact, bedding sand/gravel layer, cross bedded sand/gravel layer, silt layer, massive sand layer and a combination of layers and conditions. The complexity of the stratigraphy, multiple bedding and cross bedded sand/gravel layers, increased as the surface elevation of the sampling points decreased and approach the current surface drainage collection areas. The bedding lines of the sand/gravel remained in-phase with the clay layer as the contact surface of the clay layer became wavy.

The hard packed massive clay layer shows no indications of horizontal deposition and due to it's variance in elevation has been interpreted as lodgment till. The armored contact on the lodgment till is seen as the beginning of a subglacial meltwater flow with the smaller sediment being transported out from the bottom of the surface till matrix and deposited as a sand/gravel bedding layers in a subglacial cavity. When mapped the armored contact areas progressed from the direct contact areas and into the multiple bedding and cross bedded sand/gravel layer areas indicating a direction of subglacial meltwater flow. The preservation of the bedding structures suggest that the overlying till is the product of a passive melt-out and that the continuous till plain is a melt-out till.

Clay, silt, sand, gravel, and till deposits found below the elevation of the Maumee Shoreline within the Birmingham Quadrangle were deposited by direct glacial contact and subglacial fluvial discharge. Studies of past climate change rely upon the timing and location of ice in past glaciations; greater details of these events are needed.