45 



In some places the strike and dip of the schistosity may 

 be traced from point to point in such a way as to encircle 

 areas of granite, showing a ground plan of batholithic 

 mountain structures, domes which have lost thousands of 

 feet by later erosion, so that the relief is now comparatively 

 low. 



The Muskoka lakes, with their remnants of original 

 greenstones and their much larger area of grey or flesh- 

 colored granitoid gneiss arranged ovally about less schistose 

 centres of granite, afford typical examples of the Laurentian 

 rocks, which cover more than half of northern Canada. 

 They also show admirable examples of the lake basins which 

 occupy nearly a quarter of the original peneplane of the 

 Canadian Shield. After peneplanation had been accom- 

 plished the region was elevated some hundreds of feet and 

 rivers eroded valleys, though not to great depths. Then 

 came the ice sheets of the glacial period, scouring off the 

 debris, leaving clean, rounded and striated rock surfaces, 

 and blocking all the valleys with boulder clay or moraine 

 ridges. When the ice departed all the hollows formed 

 lakes, each of which spills over at the lowest point into the 

 next lake below as falls or rapids. The connecting rivers 

 have not yet had time to cut channels in the rock, and their 

 erratic courses add much to the beauty of the wilderness 

 of lakes spread over the Muskoka region. It is typical 

 " rocky lake " country, with lakes and ponds and inlets and 

 islands of all shapes and sizes, making a veritable labyrinth 

 of waters, which reflect rock cliffs and groves and give shel- 

 tered navigation for launches and canoes. 



ANNOTATED GUIDE. 

 Toronto to Graven hurst. 



Miles and 

 Kilometres. 



0.0 Toronto, Union station, altitude 254 feet 



2.2 m. (77.4 m.). North Parkdale, altitude 391 feet 

 3.5 km. ( 1 19.2 m.). Leaving Toronto by the Northern 

 division of the Grand Trunk railway, the train 

 passes over a drift-covered area which is under- 

 lain by Paleozoic rocks. 



