Erik Nielsen

Field mapping, till fabric analysis at 21 sites, grain size analysis, pebble counting, and heavy mineral analysis of 324 samples were used to determine the source, direction of transport, and method of erosion, transport and deposition of Nova Scotian till.

Only one major till sheet, in places showing distinct basal, englacial, and ablation phases can be distinguished in the field. It is of "classical" Wisconsinan age. Five mineral suites have been distinguished by R-mode factor analysis. The mineral suites are: 1) a detrital suite derived from post-Devonian sediments, 2) an augite suite from the North Mountain basalt, 3) an amphibole-epidote suite from the Cobequid Mountains, 4) a metamorphic suite from the southwestern and northeastern parts of the Meguma Group, and 5) an apatite-andalusite suite from the Devonian batholiths.

The mineral, pebble, and grain size distribution in the till sheet indicates generally south southeastward ice flow across mainland Nova Scotia. Generally the composition of the tills reflect that of the immediately underlying bedrock except for the red clay drumlin till deposited along the Atlantic coast which has a higher content of amphibole, augite, and mud than the surrounding till sheet. The source of the red drumlin till is the Carboniferous lowlands and the Cobequid Mountains. The red clay till was transported englacially and subsequently deposited along the Atlantic shore as melt-out till after crossing a "skip zone", an area of little or no red mud till between its source in the northwest and the drumlin fields of the east coast. The "skip zone" coincides with the drainage divide which runs down the length of Nova Scotia. Topographic high areas such as North Mountain, the Cobequid Mountains, the Antigonish Highlands, and the "skip zone", including South Mountain, were major areas of erosion.

Till fabric analysis indicates that basal ice flow conformed to the underlying bedrock topography whereas the orientation of indicator fans suggests that the regional ice flow was almost unidirectional from a source in the north northwest. Radiating dispersal fans from South Mountain and the Cobequid Mountains attest to the presence of late active Wisconsinan ice caps.

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Supervisor: H. B. S. Cooke