548 KIRTLEY F. MATHER 



less than 325 feet. In a small gravel pit beside the east abut- 

 ment of the stone railway bridge the gravels and sands are 

 overlain by bedded clays. Similar bedded clays are present 

 on the floor of the valley eroded into the fluvio-glacial gravel 

 deposits. 



At the time of construction of the Napanee valley train the 

 retreating front of the ice sheet had withdrawn less than 10 miles 

 north of Yarker, and the marine plane could not have been over 



Fig. 4. — -Napanee Valley between Newburgh and Strathcona, Ontario. The 

 cattle in the foreground and the houses and barns in the distance are on the surface 

 of the Napanee valley train. The lower flat in the middle distance is the modern flood- 

 plain of Napanee River. The exposure of fluvio-glacial gravels and sands in the escarp- 

 ment overlooking the valley fiat is in part due to gravel pits and in part to the railroad 

 which parallels the river at the foot of the scarp. Beyond the buildings in the distance, 

 the land rises abruptly to the summit of the limestone cuesta which forms the sky line 

 at the left. 



325 feet above present sea-level. Further retreat of the ice cut off 

 the supply of gravel, and dissection of the valley train commenced. 

 Subsequently sea-level waters crept upward and submerged the 

 whole region to at least the 425-foot contour line. In these waters 

 bedded clays accumulated. 



Trent Valley. — The anomalous relation between the Trent 

 Valley spillway from Lake Algonquin and the Gilbert Gulf shore 

 features has long been a puzzle to glacialists. The physiographic 



