CENTRAL ONTARIO 227 



and passes through the Black River escarpment in a narrow valley. To 

 the northeast there is another depression through which the waters of 

 the lake reach the Archean. The western wall of the valley is sharply 

 defined by a steep but not cliffed rock scarp ; the eastern side is less 

 well denned. To the south the water in the Pigeon Lake depression is 

 joined to that in Buckhorn lake through a broad channel in which there 

 is little or no current. The channel appears to be cut wholly in drift 

 deposits. The Pigeon Lake depression for 5 miles below the outlet 

 channel is flooded by the waters of the lake. Southwest of the foot of 

 the lake it is still traceable to near Omemee, where it is obscured by 

 heavy drift deposits. The stream which flows past Omemee into Pigeon 

 lake and rises about 20 miles southwest of the foot of the lake may 

 possibly mark the continuation of the depression near Omemee and to 

 the southwest. 



The principal depression whose flooded upper portion forms Buck- 

 horn lake is also a rock valley of the first type. Sandy lake, which lies 

 to the north of the west corner of the lake, also occupies a limestone 

 valley, through part of which the outlet stream from Sandy lake flows. 

 The main depression extends southwest from Halls bridge. It is well 

 marked in its northeastern extent by bounding scarps. The south- 

 western part is less well defined. This part of the basin seems to be a 

 shallow upland depression rather than one of the system of valleys in 

 which southwest running streams once flowed. The general features 

 suggest that it was drained by an obsequent stream which flowed to the 

 inner lowland in the same direction as the waters now flow. The waters 

 of Buckhorn lake connect directly with Chemung lake through a broad 

 channel bordered by very flat low-lying land. To the northeast the 

 discharge stream flows along the lowland in front of the cuesta. It 

 continues in this direction as far as Stony lake, there being two small 

 falls of a few feet each in its course. 



About midway between Buckhorn lake and Stony lake the river 

 expands into a water body known as Deer lake. The depression occu- 

 pied by this lake is bordered on either side by steep nearly vertical 

 cliffs with a heavy talus at the base — the sides of a partly submerged 

 valley of the first type. At the lower (southwest) end this valley is 

 partly obscured by drift ; but the scarps can be traced to Chemung 

 lake. About 2 miles below the foot of the lake a portion of the valley 

 is occupied by a small lake known as Mud lake. The water from this 

 lake flows in a small stream into Chemung lake, which occupies the 

 lower portion of the same valley. The rock sides of Chemung lake, at 

 the lower parts, are completely buried beneath the drift deposits. A 

 well boring to the west of the lake near Ennismore showed the rock 



XXX— Bull. Geol. Soc._Am., Vol. 15, 1903 



