麻豆传媒

The study provides detailed analysis in the lithology, texture, fabric, and geochemistry of Pleistocene tills, exposed in central Nova Scotia. Five till units are named informally. These are: The Rawdon Till, Hants Till, Bennett Bay Till, East Milford Till, and Miller Creek Till. The till units were found to have lateral integrity on a local (metres) scale at one section and were correlative regionally. Analysis of variance techniques were used to test these hypotheses. Organic beds discovered at Miller Creek, Hants County, were studied using palynological techniques.

The oldest unit in the region is probably sub-till organic beds at East Milford, Halifax County, dated at 50,000 years B.P. (GSC-1642). Pollen studies of these beds suggest an interglacial age. At Miller Creek, Hants County, organic beds underlain by a clay rich till (Miller Creek Till) and overlain by two tills (East Milford and Hants Tills) were dated at 52,000 years B.P. (GSC-2694). Palynologically, these beds do not appear to have an interglacial character, and are not correlative with the beds at East Milford. The author suggests that before a major Early-Wisconsinan glaciation, two major non-glacial intervals may be present in section.

The East Milford Till represents the deposit of a southeastward flowing ice sheet that crossed the North Mountain and the Cobequid Highlands. It contains abundant erratics derived from both these sources. It is gravel-poor and may have been derived, in large part, from estuarine muds in the Bay of Fundy. Two genetic facies are present in section, a lodgement facies with a strongly oriented fabric and local derivation, and a melt-out facies demonstrating weaker and transverse fabrics, and distant derivation.

After the deposition of the East Milford Till, during the Mid-Wisconsinan, a minor recessional period occurred. Red clays and silt were deposited. Ice divides subsequently shifted to the north of the study region. The Hants Till was formed during this period. The Hants Till is characterized by high basalt percentages, enrichment in gravel, and bimodal fabric orientation. Ice centers shifted inland in the Late Wisconsinan and the previously deposited tills were implanted with local South Mountain erratics. Ice flowing northeastward across the North Mountain created the basalt-rich Bennett Bay Till. A late westerly flow of ice produced a grey lodgement till named the Rawdon Till and many eskers and ice-contact features trending east-west in Hants County. It is perceived that these movements were not synchronous but occurred successively. The absolute ages of these ice-flow phases is unknown, but the last flow is believed to have terminated before 12,000 years B.P.

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Supervisor: H. B. S. Cooke

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