NO. 4 i'i<i;-i)i:v()NiAN si:i)imi:n'I'ai ion Km) 



(iiastr()i)liic niovciiu-iil iii.irkiii^ tlu- cl.isr of Middle ( ;iiiil)ri;ni liiiic. 

 \\ c nii^lit i-oiisidcr it a c-oiiliiiuatidii ol" tlu- How IroULili, hut as a 

 scries of scdiiiKMits were dcpositi'd in it (hat arc not found flscwlicrc 

 in the I'ovv 'I'rou^li, and wliic'li arc limited, as now known, to the 

 Sawhack, ( ilaeier Lake, and r.eaverfoid Troiij^hs, il is more con 

 venient to give it a distinct name and therehy more closely record 

 the history of sedimentation in this area of the Cordilleran Geosyn- 

 cline. Judj^inj; from (he thickness of sediments deposited (see i\g. 22), 

 this depression gradnally deepened from (he How \ alley on (he south 

 to the north-northwest as far as ( ilacier Lake and heyond, except in 

 late Middle Camhrian time. 



As now known, the ai-ea of outcrops of I Ipper Cambrian, ( )/.arkian. 

 and Ordovician sediments in this Trouj^h is between the j^reat Castle 

 iVlonn(ain fauK at John.ston Creek and the faults of (he .Sawback 

 kange .southwest of l-'orty Mile Creek, and thence north northwest 

 to the head of the Saskatchewan River drainage. (( )n the inaj) from 

 // to /•' and (/, (() li to C). 



( )n (he Hue of the headwaters of Kal I )eer River ( /' and (,' on maj) ) 

 the pre-Devonian formations include (he .Skoki ; Ordovician. Sar- 

 bach ; Ordovician (Canadian), iMons; ( )/arkian, Lyell. Hoswordi and 

 Arctomys; Upper Cambrian, and b.ldon ; Middle ( ambrian in (be 

 Sawback Ranne. The Cpper Cambrian Sherbrook. \':ii^v\, and most, 

 il uot all, of the Losworth formation were not (le])osi(ed, and (he 

 I'.ldon lime.s(one is thin and conl'ined to the eastern side of the TronKb. 



At the head of Clearwater River ( /■, on map) about .)_' miles 

 (()7.Gkm.) nor(h-nor(hvve.st of l!,,w \alley, (here is a line develop- 

 nicii( of (he .Sarbach, Alons. and Lyell f(.rma(ions, an<l (he.se are all 

 piesen( in (he (ilacier Lake Trouj^h as well as in (be I'.eaverfool 

 Trough. 



With (he close of (he period of (leposi(iou of (he ( )r(lovician. .Sar- 

 back and Skoki forma(ions, the Sawback 'lum^h ceased (o func(ion 

 so (hat the sncceedinj^ Devonian .sea occupied nearly all of (be original 

 L.ow Trough area, (be (ilacier Lake 'Irough, and much .,f (he ana 

 of (he l'.eaverfo()( Trouf^di. 



(;i.A( n;ii laki: ikouch 



The formations deposited in this Trough were studied in the ( .lacier 

 l-ake area (B, C, and /; on map) about (he headwa(ers of (he Sas- 

 katchewan Kiver, 54 miles ( S^mj km.) nor(h-nor(hwe,st (,f (he Mow 

 I rough .section ainl ,.>() miles (i<;.^, km.) .sou(bsou( beast of (be 

 kobsou Leak l)is(ric( sec(ion. The (ypical sec(ioi, of (be lonna(ions 



