132 A. p. COLEMAN MARINE AND FRESHWATER BEACHES 



all the way up. The sand rests conformably on the clay, and rises to a 

 level of about 350 feet above the sea. The surface of the adjoining 

 countr}^ is sand}'^, with a somewhat rolling and duny character, but 

 without any well marked shoreline ; so that the sand was probably laid 

 down as shoals in shallow water. 



Siinilar sands with shells are reported by Doctor Ells at higher points 

 farther up the Ottawa — that is, at 470 feet along the summit of rocky 

 ridges to the west of Arnprior. 



The sands occur widely spread also in the flat country south of Ottawa, 

 good instances being seen along the Nation river audits tributaries near 

 the villages of Avonmore and Monklands, w^here drainage operations 

 give good opi)ortunities to study them. Here one finds broad, swampy 

 tracts more or less covered with peat, beneath which is a layer of sand 

 from 2 to 5 feet thick, crowded with shells of saxicava and macoma and 

 resting directl}^ on bluish boulder-clay with no stratified clay interven- 

 ing. In some places a layer of sand, containing many small freshwater 

 shells of at least eleven sj)ecies, rests on the marine sand with no appar- 

 ent break between the two, so that the same spadefull contains both, 

 though there must have been a considerable lapse of time between the 

 formation of the two layers of sand. At some points on the drainage 

 ditch tlie boulder-clay is missing, and the marine sand, with shells, rests 

 directly on the flat limestone of the region, the boulder-cla}'' having been 

 removed ]>erha])s by erosion. These sand beds are from 320 to 330 feet 

 above seal ev el. 



' The association of freshwater with marine shells in different beds of 

 the same section is, of course, not a new thing, since Sir William Dawson 

 long ago mentioned similar relationships in stratified clay and sand at 

 Pakenham, northwest of Ottawa.* 



Shell-bearing Gravels 



Still more frecpient than shell-bearing sands are banks and ridges of 

 gravel containing the same fossils — Saxicava gravels, as they may be 

 called — wliich often have a substratum of boulder-cUw, and in many 

 cases consist of morainic or kame-like deposits, probably of glacial origin, 

 rearranged by wave action. Many of these ridges are found in the 

 neighborhood of the villages of Finch and Avonmore, and they are often 

 elongated in a direction of about north 15 degrees or 20 degrees east, which 

 corresponds to the general direction of the glacial stride of the region. 

 They are not eskers, however, being too short and consisting often of a ridge 



* Can. Ice Age, p, 58. 



