THE SLX'CKSSION Ol' DEPOSITS. 59 



found nil llu! Cliiiudiriv laki', 1M;' feet alxive lake St. 

 iV'tcr.s, oil the ^laduwaska HOO feet, aiul at Fort C'oul()ii,u,e 

 lake oiji) feet above tlie same level, u verv intere.stin<' 

 indication of the gradual recession of the capidin spawn- 

 ing grounds from this last hiuli elevation to the level of 

 the more celehrated locality of these fossils at (Ireen's 

 creek. Farther, throughout tlu; counties of Renfrew, 

 Lanark, (.'arlet on and Leeds, the marine deposits rise to un 

 elevation of 42.") feet, or nearly the same with one of the 

 terraces on Montreal mountain : Imt while this eleva- 

 tion would, with the ]»reseiit le\t'ls of the countr}-, carry 

 a ileep sea to the h'-ad of lake ()nlario, no marine fossils 

 a})pear to ha\e been found on the l)anks of that lake. 

 Was the depression of the lat<'r I Meistocene period limited 

 to the country east of lake Ontario, or have the marine 

 deposits of the u])])er St. T.awreiice hitherto escajK^l 

 (thservation or been remo\ed l»v denuding agencies ? The 

 c[uestion awaits further explanations for a satisfactory 

 answer. 



3. — T/ii' Bi(.i:iriira SdinJ, ninl Uppir Bm/hJrr Dcjtosif. 



AVhen this deposit rests upon llu' Leda clay, as is not 

 unfre([uently the case, the contact may be of either of two 

 kinds. In some instances the surface of the clay has 

 experienced much denudation, being cut into deep 

 trenches, and the sand rests abrui)tly upon it. In other 

 cases there is a transition from one deposit to the other, 

 the clay becoming sandy and gratlually passing u])vvards 

 into pure sand or Hue gravel. In this last case the lower 

 part of the sand at its junction with the clay is often 

 very rich in fossils, showing that after the deposition of 

 the clay a time of quiescence supervened with favourable 

 conditions for the existence of marine animals, before the 



