TOrOGKAPHT OF THE KONA DOLOMITE. 241 



and extends westward as a belt a third of a mile wide. As it reaches Carp 

 River the formation swings southwest, and then south to Tigo Lake. Here 

 a small arm goes to the southeast across this lake toward Lake Mary, but 

 the main belt continues to the southward. About a mile west of Lake 

 Mary it widens out into a broad area, varying from a mile to 2 miles in 

 width, and extends to Goose Lake, the last exposures of the formation being 

 found on the east side of this body of water. Also north of the Archean 

 island in sees. 2 and 3, T. 47 N., R. 25 W., the limestone appears, just north 

 of the Mesnard quartzite, in a narrow belt. The real extent of this area of 

 dolomite it is impossible to give, as the Potsdam formation occupies much 

 of the valley of the lower reaches of the Carp River. 



Almost coextensive with the distribution of the formation are the 

 exposures, they being abundant and prominent throughout most of the area. 

 How^ever, some of the most readily accessible places at which the formation 

 may be studied are the exposures east of Goose Lake and those south and 

 west of Wabassin Lake (Atlas Sheets XXXIV and XXXIX). 



As a consequence of the conqilicated folding of the formation, below 

 described, combined with the very different resisting- powers of the layers, 

 the topography of the formation is exceedingly jagged. The exposures 

 constitute a set of sharp and aljrupt cliffs, cut by i-avines or separated 

 by drift-filled valleys. Where north-south and east-west folds both occur 

 the valleys cut across one another in two systems at right angles, leaving 

 roughl}' rectangular masses of rock between. In places where the folds 

 have a pitch the lavers may form semicircular outcrops with vertical walls. 

 Rather low dips prevail for much of the area, and in traveling over the 

 belt one has to climb a series of steep hills, each of which is composed 

 of a number of almost vertical, ragged cliffs. The descent from the eleva- 

 tion is of much the same character. The weathered surfaces of the ledges 

 also are sharp and ragged in a minor way (PI. VII, fig„ 1). The cherty 

 layers form sharp ridges. The quartzite layers project in less jagged forms. 

 Geodal concentrations of quartz protrude from the surface of tlie hmestone. 

 The dolomite has dissolved from the cherty and quartzose layers, giving 



them a rough, vesicular appearance. 

 MON xxviii IG 



