M. Mi INK I )i: POSITS 131 



creek and Besserers wliarf a few miles down the rivor. The ehiy, which 

 is bhiisli gray aiul well stratitied. rises ahout 40 feet ahove the Ottawa, 

 or about KU) feet ahove the sea, and contains in many places f];reat num- 

 bers of concretions, well known for the beautifully preserved fossil fish 

 they often enclose. In addition to the capelin {iWdlotus villosas) and two 

 or three other fish, Lcdd (irctiai, Sd.cicavd rnffosd, and Mdcoma frag'dU^ witli 

 some other si)ecies of shellfish, have been found in the concretions. From 

 brickyards in the city a number of other fossils — shellfish, a sj)onge, 

 foraminifers, etcetera — have been obtained. 



In addition to the marine forms mentioned, a large number of land 

 and freshwater plants and several l)irds and mammals, including a seal 

 and a chii)munk, have been obtained from the concretit)ns, showing that 

 the Leda cla}"^ was formed not far from a shore where clay, with drift 

 materials, was brought down by rivers. Although Leda itself may occur 

 in moderatel}' deep water, most of the other fossils suggest shallow water. 



In Nepean townshi]), G miles up the Rideau river from Ottawa, the 

 Leda clay rises to about 310 feet above sealevel,but here no concretions 

 are found, and the number of species of shellfish is small. Leda clay 

 with concretions is found 60 miles northwest of Ottawa city, on lake 

 Coulonge, an ex})ansion of Ottawa river, at a height of 370 feet above 

 the sea, according to Doctor EUs,'^ and at many points down the river 

 and along the Saint Lawrence. Very similar stratified clays occur at 

 levels above this, even up to 1,000 feet, but marine fossils have not been 

 reported in them above 370 feet. The fossiliferous clays near Ottawa are 

 stated to be 140 or more feet in thickness, and as they are very widely 

 spread, their deposit must have demanded a long time. Tlie Leda cla}'" 

 of Montreal and points farther east and northeast along the Saint Law- 

 rence, which will not be referred to here, has been well described by Sir 

 William Dawson in " Canadian Ice Age." 



The Saxicava sands cover a greater area than the clays, but contain 

 fewer species of fossils, the usual ones being S'axicava riigosd and Macoma 

 frdgilis, whose white, but well preserved, shells could sometimes be col- 

 lected by bushels. A good ex[)osure of these sands occurs at the ))oint 

 6 six miles from Ottawa, on the Rideau river mentioned before, where 

 overlying the clay there are about 40 feet of sand, showing more or less 

 cross-bedding and evidenth' deposited in shallow water. 



Beside the two ubiquitous shellfish mentioned above, many shells of 

 Mytllus edulis occur, often beautifully preserved with the two valves still 

 united; and one finds also a few balani. The shells are most numerous 

 just where the sand and clay join, but are found more or less frequentl}'' 



*Sands and Clays of the Ottawa Basin, Hull. Geol. Soc. Am., vol. 9, pp. "ilo and 21C. 



