POST-GLACIAL STRATIGRAPHY AND SAND RESOURCES IN THE WESTERN BASIN OF LAKE ERIE

A sedimentary sand unit lies beneath one-third of the Lake Erie Western Basin ranging from a few meters to eight meters thick. Previous investigations relying solely on jetted holes stated that this unit is a delta from the Detroit River deposited 4,000 years ago. The current study used jetted holes, vibratory cores and marine seismic technology to examine the size, composition, and origin of the sand. A total of six sediment facies have been identified. Several of the units can be traced regionally throughout the basin. These units include, starting at the water sediment contact: modern lake mud, peat, sand, glacial lake clay, till and finally bedrock. Each facies represents a slightly different depositional environment for the location then is currently present. The recent lake mud consists of soft, semi-fluid, silt- and clay-sized particles. The sand unit is primarily well-sorted (clean), medium- to fine-grained material with some gravel. The peat is of particular importance to determine the timing of depositional events leading toward lake level changes. The peat is a rich dark brown plant detritus that indicates the prior widespread existence of a low-energy paludal or lacustrine environment in Western Lake Erie. This represents a non-glacial low-level lake or swamp environment. Lewis (1969) dated the peat layer within our study area at 11,430±150BP (I-4035). This date lies within the “Early Lake Erie” lake level interval. The underlying sand must be older then the “Early Lake Erie” lake level. The glacial lake clay that is below the sand unit correlates to previous lakes in the Western Basin such as Maumee, Arkona, Whitlesey, Warren, etc. Evidence of channels that have been filled are present in many of the units, especially the sand. These channels are common and support the theory that the Western Basin either was dry or held a shallow marshy lake approximately 12,000 years ago. The study was conducted to define glacial stratigraphy in the Western Basin and locate potentially economic sand resources. To aid in the depositional environment determination and sediment unit mapping, a Geographic Information System is being used to create maps of facies distribution, thickness, and depth.