62 



TllK UK .\<;K I.\ CANADA. 



/ 



V 



&m I 



I 



■'f,i 



!l k 





\ - 





ir 



siiiiic I'L'ct'ssioii (if ihc st';i wliicli 

 Itidduccd the SaxiciiNa siind. At 

 ^Mdiitical, where tlu; isdlatcd mass 

 I'l' Map llaiikcd wiih Inwcr Silurian 

 beds, ediisiiiiiliii.n' Mniiiit llovid, 

 forms a y^wwi lide-o-au^fe fur the 

 recession of the rusL-plioeene sea, 

 thei'eai'c fnnr jtrineipal sea margins, 

 with several others less distinctly 

 maiked. The lowest of these, at a 

 level of ahout TJO feet al)ove llu' 

 le\('l of the sea at lake St. Teler, 

 may he considered to corresj)ond 

 with the .ueiieral level of the ^reat 

 l»lain of I.eila clay in this part of 

 < 'anada. ( »ii this terrace in many 

 places the Sa.\ica\a sand forms tlii' 

 surface, and the Leda and liouldei-- 

 clay may be seen beneath it. This 

 may lie called at Montreal tlu' Sher- 

 bidoke Street tcriace. Another, the 

 AN'ater-work terrace, is about 'I'li) 

 feet hijj,h, and is marked by an 

 indentation on the lower Silurian 

 limestone. At this level some 

 boulder-clay appears, and in ]ilaces 

 the calcareous shales are decom- 

 jxised to a p'eat de])tli, evidencing 

 long sul)-aerial action, 'i'liree other 

 terraces occur at heights of ."kSG, 

 440, and 470 feet, and the latter 

 has, at one })lace above the village 

 of Cote des Xeigcs, a beach of sand 



