Date of Award
1982
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Abstract
Stratigraphic and sedimentologic studies of the Port Stanley Drift, near Port Stanley, Ontario, have revealed a sequence of glacier advance and retreat, concomitant with the development of multiple phases of Lake Maumee. In the course of the retreat of the Port Stanley glacier during the Port Bruce Stadial, a thick (18+ m) sequence of clay-silt tills was deposited in the study area. These tills are informally designated the lowermost Port Stanley Till. Two subunits are recognized: unit A, a massive till correlated with subglacial depositions, and unit B, a waterlain facies comprising till, fine-grained rhythmites, and current-bedded sand and silt. Till granulometry, pebble lithology, carbonate mineralogy and till fabrics (ESE to WNW maxima) indicate derivation mainly from bedrock and older drift within the Lake Erie basin. The lowermost Port Stanley Till is overlain, successively, by 5-7 m of fine-grained rhythmites, and 10-15 m of varved and non-varved glaciolacustrine sand of Lake Maumee III. Individual varves are 41 to 166 cm thick, and comprise Nu-cross-stratified medium sand to coarse silt in the summer layers, and fine silt and clay in the winter layers. The summer layers were deposited by tractive currents, and derived from the Catfish Creek Drift, as indicated by the provenance of heavy minerals, and calcite/dolomite ratios. A larger component of reworked Port Stanley Till is manifested in the clay mineralogy of the winter layers, which were products of suspension fallout. One particular body of till enclosed by the Lake Maumee III sands, the "upper till complex", was studied in detail to elucidate till genesis in glaciolacustrine environments. An origin by subaquatic slumping and flowage is proposed for the upper complex, based on the presence of stratified till, containing curent-bedded sand and silt, "turbidite-type" sole marks on the base of the tills, flow and hook folds, and rip-up clasts of soft sediment. Other structures in the upper complex, including upsheared lenses of sand, and till fabrics, are not unequivocal indicators of flowage. Of the structures studied, certain ones (sole marks, sheared sand and silt lenses) are commonly smeared out and attenuated in till by lodgement processes, whereas others (current bedding, hook and flow folds) will be rare or absent as primary structures in lodgement tills.
Recommended Citation
Stewart, Robert Arthur, "Glacial And Glaciolacustrine Sedimentation In Lake Maumee Iii Near Port Stanley, Southwestern Ontario" (1982). Digitized Theses. 1220.
https://ir.lib.uwo.ca/digitizedtheses/1220