A reconnaissance survey of that part of the Scotian Shelf extending from Halifax to Digby Neck was conducted during October, 1961, in order to determine the nature, distribution and source areas of the bottom sediments. The compilation of a bathymetric map revealed the complex topography of this part

End_Page 210------------------------

of the Shelf. On the basis of morphology, several physiographic regions have been defined. The western area from Shelburne to Digby Neck is quite irregular with many ridges, knolls and small valleys. Off Halifax the presence of two deep, approximately north-south trending basinal areas separated by a rather high ridge has been observed. A deep-water channel region approximately parallels the shore at 25 to 40 nautical miles from the coast; this channel separates the nearshore part of the shelf from the smooth, moderately shallow banks area that extends along the outer reaches of the shelf. Bottom profiles of each traverse across the shelf have confirmed the physical expression as interpreted from the contour map.

A visual percentage analysis was made of the various grade sizes in the samples obtained on the oceanographic cruise. From the data a preliminary sedimentary distribution map has been constructed. From this preliminary examination there appear to be several factors exerting an influence on the texture and distribution of the bottom sediments: topography, depth of water, the action of waves, tides and bottom currents, and the effects of Pleistocene glaciation. In general, the fine-grained deposits of silt and clay (pelite) are found in the basins on the shelf as well as in the deeper water at the upper edge of the continental slope. Coarse-grained deposits in the form of sand and gravel are irregularly scattered over the whole area and appear to characterize topographically high areas. Sand and gravel are found along the shelf margin, the finer fractions being conspicuously absent. Wave action may be a contributory factor in removing the finer deposits.

Rocky areas, particularly south of Yarmouth, have been inferred from the difficulty in obtaining bottom samples as well as from published data (hydrographic charts, reports, etc.). Since the adjacent continental area has been subjected to Pleistocene glaciation, consideration has also been given to the possibility that present-day sediments could be reworked glacial debris with the admixture of Recent sediments.

The heavy minerals (sp. gr. greater than 2.89) have been separated from those samples showing a definite sandy texture (particles from 0.0625 mm. to 2.0 mm.). Permanent mounts have been made of the heavy fractions for mineralogical studies.

End_of_Record - Last_Page 211-------