A MESOZOIC FOSSIL FLORA FROM ARCTIC ELLESMERE ISLAND

Abstract

Much of the Arctic at the present time is barren of plant life or is frozen for much of the year. Evidence of arctic fossil floras ranging from Devonian to Tertiary in age shows, however, that these conditions only became widespread in this region during Pleistocene times. Many of the genera and species found in late Cretaceous and Tertiary floras have a warm-temperate or tropical distribution at the present time. Palaeomagnetic and palaeoclimatic evidence indicates that the position of the poles relative to the land masses has changed through geologic time (Jacobs, Russell, and Wilson, 1959, p.141). A number of theories, for example, Continental Drift (Du Toit, 1957) have been postulated to account for this. Arctic palaeobotany presents great problems of collection and geological correlation. Palaeobotanists themselves have collected only in parts of Greenland (Heer, 1368; 1880; 1883), (Seward, 1924; 1926), (Karris, 1932-1935); Alaska, (Heer, 1871), (Hollick, 1930; 1936); Spitsbergen (Heer, 1877), (Nathorst, 1894, 1897); and Ellesmere island (Radforth, Andrews, and Phillips, 1963). Floras from other areas have been investigated briefly by passing exploration parties whose collections were often small because of the cost and difficulties of transport. floras from geologically little known areas are difficult to date. Greenland, palaeobotanically the most fully investigated region of the Artic, has a number of fossil floras ranging from Devonian to Tertiary in age. On the west coast is found the controversial Rome flora of Lower Cretaceous age containing possible early angiosperms. The age of the strata containing the Kome flora has been recently worked out by Koch (1964). On the east coast of Greenland is found the Rhaeto-Liassic flora of Scoresby Sound which has been described in great detail by Harris (1926-1957). It shows similarities with Rhaeto-Liassic floras from Germany and Sweden (Harris, 1931). In recent Arctic studies emphasis is being placed on palynology (Manum, 1954; McGregor, 1961) because of the stratigraphic significance of miospores and their widespread occurrence in strata otherwise barren of fossils. The Objectives of the Present Investigation The fossil plant material examined in this thesis came from a previously unexamined deposit of probable Mesozoicc age from Ellesmere Island in the Canadian Arctic. In this investigation there were three main aims: 1. A description of the specimens, their identification wherever possible, and a discussion of the taxonomic significance and relation hips of each. 2. The dating of the deposit using the stratigraphic ranges of the plant macrofossils and miospores obtained from the rock matrix, and the comparison of these results with those obtained from this area by other workers. 3. The comparison of the flora with other floras of a similar geological age.