60 '111'" i< "•• ■\"i' '^' <'.\\.\i»,\. 



slwHild mil lie ii('^lt'(ii'(l liy gcdlogists. I Lliiis lelVrrcil to 

 il ill lS(i4.* 



" ( )iir Aiiicricaii liikc-ltiisins iiic ciii mit dcciily in tlic 

 sitftcr striita. Kiiiiiiiim' wntcr mi tln' laml cdiilil ikiI Iiunc 

 iloiir iliis umlci' tilt' |nrs('iii L;('(in|'j||ilii(.;il (■(inditioii.s. 

 tli<Mi<,'li il L'oiild t'Hi'ct il, Willi a liiLilici level miil Itcltcv 

 drill IlilU'c : mil' cniild ihc icsnil In- ctrcclrd liy nccau 

 l)rt'iiki'i's. llii>n;4ii ilic l('\(dliii^ jinwcr df ilicsc i.s I'lKtiiiiniis. 

 (llaciei's ciMiIil iini lia\t' cni'dcil it: I'm' cscii if (lie 

 (diiiialal coiidii imis for ilicsc were adiiiitlcd, I lici't' is im 

 lici,^lil (if land to i^i\( lliciii iiidiiicniuiii. Iliit if wi- 

 siij)it(is(' the laml snlniicrp'il so ilial llif arctic cnrrciit, 

 tjowiii^ fnmi the inirtli-casi, shoidd |i(Mir ()\ cr the Laiii'- 

 ciitiaii I'dcks nil tlicmutli side of lake Suiiciiin' and lake 

 lliii'oii, it Would necessarily cut out of ilic softer Silurian 

 strata just such liasins. driflin^ their niateiMuls to the 

 south-west. Al the siiuie lime, ihe lower strata i>\' the 

 eui'i'dit W(HiId lie |iowerfulIy ilelei iniiieil thrdu^h the 

 strait lielweeii the Adiioiidac and Lanreiilide hills, and 

 I'unnin^u,' o\er the ridiic of hard rock which connects theni 

 at the Thousand Islands, wouM cut oui the loii^- hasin of 

 lake < )iitario, liea[iin,n' \\\> at the same lime in the lee of 

 tlu! Laui'entiau rid.uc, tin- eicaL mass of lioiilder-eliiy 

 wliieli intervenes lietweeii lake Ontario and (!eor<,duii 

 hay. Lake Krie may have hei'U eut hy the How of the 

 upper layers of water o\er the Middle Silurian escarp- 

 ment : and lake Michiuan, tliouuh less closely connocted 

 with the direction of the current, is, I'ke the others, due 

 to the action of a eoniinuoiis eroding forct' on rocks of 

 uueipial hardness. 



* Presidential Address to Nat. Hist. Soc. of ^fontreal, Canadian 

 Xaturalist, 18U4. 



