STRIATED ROCK SURFACES. 61 



Annapolis, and deposited on the slopes of the opposite trappean ridge ; 

 and some of them have been carried round its eastern end, and now lie 

 on the shores of Londonderry and Onslow. So also, while immense 

 numbers of boulders have been scattered over the south coast from 

 the granite and quartz rock ridges immediately inland, many have 

 drifted in the opposite direction, and may be found scattered over the 

 counties of Sydney, Pictou, aiul Colchester. These facts show that 

 the transport of travelled blocks, though it may here as in other parts 

 of America, have been principally from the northward, has by no means 

 been exclusively so ; boulders having been carried in various directions, 

 and more especially from the more elevated and rocky districts to the 

 lower grounds in their vicinity. Professor Hind has shown the 

 existence of a similar relation between the boulders of New Brunswick 

 and the hilly ranges of that country. 



As might have been expected, the removal of these travelled 

 masses has occasioned important changes of the surface, or, to use the 

 ordinary geological term, there has been very extensive denudation in 

 the production of the boulder deposits. A very large proportion of 

 the present features of the surface indeed result from this cause ; the 

 ridges of Cumberland, the deep valley of Cornwallis and Annapolis, 

 the great gorges crossing the Cobequid Mountains and the western 

 end of the North Mountains in Annapolis and Digby counties, such 

 eminences as the Greenhill in Pictou county, and Onslow Mountain in 

 Colchester, are due in great part to the removal of soft rocks by 

 denuding agencies of this period, while the harder rocks remained in 

 projecting ridges. On the other hand, it might be shown that many 

 masses of rock which once projected above the surface have been 

 greatly diminished or entirely removed. 



One of the most remarkable effects of the ti-ansport of surface 

 materials is the scratching and jjolishiug of rock surfaces, a phenomenon 

 which prevails very extensively over the northern parts of America 

 and Europe, and may be frequently observed in Nova Scotia. Indeed 

 it is the rule rather than the exception, that when a fresh rock-surface 

 is uncovered by the removal of the boulder clay, it is found to be 

 smoothed and marked with stria;, scratches, and furrows, usually in a 

 uniform direction ; the whole being evidently the result of the passage 

 of heavy and hard substances over the surface. These scratches or 

 furrows are useful as indicating the direction in which the mass of 

 superficial detritus has been moved; and I have even used this 

 direction with success in tracing useful minerals found in fragments 

 among the drift to the sources whence they were derived. I give 

 below the directions of the diluvial scratches in a number of localities 

 in different parts of the province. 



