292 Ooldthwait — Twenty-Foot Terrace and 



are met with in many localities along this southern shore, from 

 Riviere du Loup to the Magdalen River. A low terrace, about 

 five feet above the highest tides, and averaging about 100 

 yards in breadth, extends, with a few interruptions, from 

 Rimonski to Whale Cape, a distance of seventy-five miles. It 

 is composed of sand, gravel, and broken shells, and makes a 

 good roadway, as well as a productive soil. The shells in this 

 terrace are of the same species as now inhabit the adjacent 

 waters. Besides these, bones of the whale and the morse have 

 been found partially imbedded in this deposit, in several places 

 between Bio and Matanne. At Ste. Anne des Monts, five or six 

 terraces rise one above another to a height of about twenty-five 

 feet above the sea. All of them abound in fragments of shells, 

 belonging to the common littoral species." 



This statement, half concealed by the detailed information 

 on Champlain or " post-Tertiary" deposits, with which several 

 pages are filled, escaped close attention from the present 

 writer, when looking over the literature, before entering the 

 field, in June, 1910. The more detailed reports of the late 

 Dr. R. M. Chalmers,* although full of references to marine 

 terraces at heights of from 200 to 800 feet, gave no hint of an 

 important terrace at so low a level. The discovery of this 

 conspicuous sea-cliff and bench, on the second day of field 

 work, came therefore as a complete surprise. 



The importance of the twenty-foot terrace rests mainly upon 

 these facts : it is a mature shoreline, while the extinct shore- 

 lines above it and the modern one below it are comparatively 

 infantile ; it extends over a wide area, certainly more than 225 

 miles down the Saint Lawrence from Quebec, and presumably 

 around a considerable part of the adjoining coast of the Gulf. 

 The significance of the terrace, as will be shown in the follow- 

 ing pages, consists in the possibility that it marks a long period 

 of slow coastal subsidence, which followed the first great emer- 

 gence from the Champlain sea, and which was itself followed 



*R. N. Chalmers : On the glaciation and Pleistocene subsidence of north- 

 ern New Brunswick and southeastern Quebec. Transactions of the Eoyal 

 Society of Canada, vol. iv, sec. iv, 1887, pp. 139-145. 



Pleistocene marine shorelines on the south side of the Saint Lawrence 

 Valley. This Journal (4), vol. 1, pp. 302-308, 1896. 



Surface geology and auriferous deposits of southeastern Quebec. Geo- 

 logical Survey of Canada, Annual Report, vol. x, part J, No. 670, 1898. 



Surface geology of the southern part of the province of Quebec. Geo- 

 logical Survey of Canada, Summary Report of the Director for 1903, pp. 

 140-143. 



Surface geology of eastern Quebec. Ibid., Summary Report for 1904, pp. 

 250-263. 



The geomorphic origin and development of the raised shorelines of the 

 Saint Lawrence Valley and the Great Lakes. This Journal (4), vol. xviii, 

 pp. 175-179, 1904. 



Surface geology of the Saint Lawrence Valley. Geological Survey of 

 Canada, Summary Report of the Director for 1907, pp. 69-71. 



