AN OVERVIEW OF THE PALAEONTOLOGY OF AN INTERGLACIAL SINK HOLE NEAR MILFORD, NOVA SCOTIA, CANADA

Discovery of mastodons (October 1991 and July 1993) in an area of gypsum sink holes during mining at National Gypsum (Canada) Ltd.’s quarry located near Milford, Nova Scotia lead to the unearthing of a variety of other flora and fauna. Sixty-five percent of a 22 year-old mastodon and approximately 5 percent of a six year-old juvenile were excavated.

Sink hole development ranges in age from late Cretaceous (R. Fensome personal communication) to late Pleistocene. After development, sink holes were rapidly filled with fresh water pond sediments, including clay, silt, sand and cobbles.

There were two distinct modes of preservation observed in the two sink holes containing the mastodons. In the deep, first hole, the sediments were primarily dense, finely bedded clays with occasional sand and pebble units. The second hole was much shallower and contained pebble and sand units with occasional clay beds. The first was a “wet-bone site”, that is, no petrifaction had taken place in the vertebrate material. The second site was quite different and extraordinary. All vertebrate material was permineralized. As well, preservation of actual material was prominent in several specimens. A dung blanket from the second site contained mastodon dung that still had a powerful smell resembling that of modern elephant dung. In contrast, some dung balls were totally petrified. The juvenile mandible, when being cleaned, revealed masticated wood fragments incorporated in a depression in a molar. In both holes, thousands of Red Spruce cones were found which upon drying, would open and then shed their seeds. Tree trunks and branches were common, more so in the first hole than in the second. All trees and branches were compressed to an oval cross-section and some showed evidence of browsing. Most trees were not mineralized in any respect, except in the rare case of small sections of trunks and branches, a few centimetres in diameter, being mineralized. Sub-Arctic species of gastropods (D.S.Davis personal communication) were recovered from the upper-most beds of the first sink hole.

A great deal remains to be done on the information gathered from this truly marvellous site.