215 



advance of ten feet toward 1 ho center of the swamp there was an increase 

 of one foot in the depth of the peat. If this slope continues to the center, 

 a depth of 117 feel would be attained. The evidence cited does not prove 

 that the slope is so uniform nor that the depth mentioned did exist, but 

 approximately such a depth is probable. 



Here was a lake of considerable depth surrounded by a very level 

 plain (the older lake bottom), with an outlet over a mile in length, and 

 with shores of slight slope. What was the cause of its extinction? 



Fig. 6. Drosera intermedia. 



Description of the Swamp Proper (Fig. 1). — The drainage lines of the 

 swamp begin at the northwest corner and extend around near the mar- 

 gins to the southeast corner. The central part is slightly elevated above 

 the remainder. 



These facts indicate that the plants are more vigorous in the center 

 than near the margins. This elevated portion has in its center a U- 

 shaped area of tamaracks (Larix Americana), with the open end of the 

 U pointing northward. Most of this northern opening has been due to 

 artificial disturbance. The primary drainage-lines are on the east and 



