246 A. p. COJvKMAX TlIK EAKLIKST 1 N TKK-f : LA( lAL PERIOD 



tween the sand layers there are great numb<^rs of leaves of deciduous trees, 

 usually perfectly preserved, though hard to extract as complete leaves 

 because of the difficulty in splitting the clay in precisely the right way to 

 expose the whole of a leaf. Hundreds of leaves have been obtained, and 

 most of the 35 species of trees reported from these beds have been deter- 

 mined from them. The leaves evidently settled to the muddy bottom in 

 quiet water. They were not crumpled nor wcatlicred nor tmii bei'oi'o 

 they were embedded, and the organic niattci' is still preserved as a thin 

 brownish layer. 



Above the highly fossiliferous beds there are ;J feet of blue sandy chiy, 

 with fewer shells, and 5 feet of brown sand which occasionally contains 

 wood. The brown or yellow sand is more or less cemented witli iron 

 oxide and must have been formed in shallow water under oxidizing con- 

 ditions. The whole thickness of beds at the brickyard is about 25 feet, 

 but including the beds in the old rivei\ channel half a mile east at the 

 bend of the Don the thickness becomes 40 or 45 feet. 



Blue, finely stratified clay, resting evenly on the l)rown sand and rising 

 for 23 feet at the brickyard, is considered to rei)i'esent the lowest Scar- 

 boro beds. 



The Bon beds occur over almost the wliole area of Toronto and haxc 

 been found 14 miles to the north at Thoridiill. where wood, a pine cone, 

 and shells Avere obtained, after penetrating a great thickness of till, in 

 stratified sand and gravel 200 or 300 feet below the surface. The warm- 

 climate beds have been found also in a well at Scarboro Heights. 7 miles 

 east of the Don. The kno«ai width of the l)eds near Lake Ontai-io is l:! 

 miles, and with a length of 14 miles iidand the area ciin hai-dly he less 

 than 100 square miles and may be much greater. 



The natural explanation of the facts just described is iluil nflei' I he 

 earliest ice-sheet had withdrawn for ;i limc long enough for a stream to 

 ciit a valley 16 feet into shale and to allow forest trees like those of Penn- 

 sylvania to reach the Don Valley, the outlet of the Ontario basin was 

 slowly lifted, ponding back the waters so as to form a lake, which grad- 

 ually rose to a height of 50 or 60 feet above that of Lake Ontario. Unios 

 and other shell-fish, some of them Mississippi forms, throve on the mnddy 

 bottom ; floating tree trunks got water-logged and sank into the mud, and 

 all were buried under sand and clay brought by a great river from the 

 north. Fresh trunks and leaves from trees that grew on the banks of the 

 river were carried down from time to time during hundreds or thousands 

 of years, all being quietly entombed in the beds of the growing delta, and 

 with them were preserved bones and horns or tusks of extinct mammals 



