Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/360

 S. 35° W. Other less strongly-marked striae varied slightly from this common direction.

On the road from Belleville to Shannonville, on the first concession of Thurlow, between Lots 24 and 25, I have observed the direction of ice-marks on the outcropping Trenton limestone to be E. 85° N. and W. 85° S.

A careful study of the deposits here grouped together as " drift " would apparently lead to the conclusion that their formation is referable to the action of two distinct agencies — the one a force similar to that of land -ice pushing before it an accumulation of northern rocks, whilst it rounded, polished and grooved the country over which it swept, and the other an action similar to that of icebergs scattering their freight of gravel and angular fragments of rock over the bed of the sea. The eastern half of the township of Hungerford, and the northern ranges of Huntingdon and Rawdon, are thus covered with scattered angular blocks of limestone removed from the Laurentian area, some of the blocks exhibiting distinct glacial markings. Between the period of glacier ice and that of floating ice the stratified sands and clays appear to have been deposited in comparatively tranquil water.

3. Lower Silurian. — In the South Riding of Hastings is an extensive development of that division of the Lower Silurian formation distinguished as the Trenton group, including under that name not only the Trenton Limestone proper, but also the Bird's-eye and Black-River Limestones. The upper portion of the Trenton group consists of a series of thin-bedded shaly limestones, occasionally interstratified with beds of calcareous clay, and highly charged with the characteristic fossils of the Trenton Limestone. These rocks generally strike in an east and west direction, and are for the most part horizontally bedded, or have only a gentle dip to the south-west, with occasional evidence of a slight upheaval. In the shallow valleys of denudation which in many places intersect the county, sections of these limestones are occasionally exposed ; but as a rule they are almost completely obscured by a covering of drift.

The thin -bedded fossiliferous Trenton Limestones rest conformably upon a thick-bedded limestone almost destitute of fossils, only three species having hitherto been detected. Probably this thick-bedded limestone represents the Bird's-eye and Black-River series. Sections are exposed along an escarpment, varying from 50 to 100 feet in height, which forms the junction of the Trenton beds with the underlying Laurentian rocks. This escarpment gives direction to the drainage from the Laurentian watershed of this part of Canada.

The total thickness of the Trenton Limestone at Belleville may be estimated at about 800 feet. A boring to the depth of 600 feet was sunk about 15 miles S. W. of Belleville, in the County of Prince Edward, without reaching the base of the series ; and another boring, 7 miles north of Belleville, 500 feet deep, was attended with a similar result.

Whilst the Trenton group of rocks is almost confined to the southern part of the county, it is notable that two large outliers of