434 Leverett — Observations on Craigton Lake. 



mere fact of the abandonment of the Big Prairie channel. 

 There is found, however, direct evidence that the Lake Fork 

 outlet was a little the lower. Between Funk and the hamlet 

 of Lake Fork the highest bar or shore feature that seems refer- 

 able to Craigton Lake barely catches the 960-foot contour, 

 and seems to mark a high-water stage, just as the one at 967 to 

 968 feet near the head of the Big Prairie outlet is interpreted 

 to have done. There is likely, therefore, to have been a drop 

 of about seven or eight feet when the Lake Fork outlet was 

 opened, and because of this the discharge through the Big 

 Prairie outlet naturally ceased. 



The head of the Lake Fork outlet is about four miles far- 

 ther north than that of the Big Prairie outlet, and on Pro- 

 fessor Hubbard's hypothesis, the shore there should have been 

 about 16 feet higher, yet as indicated above it is really slightly 

 lower, and such difference in altitude as the shore presents is 

 easily explained by the shifting of the outlet. Inasmuch as 

 the real limits of Craigton Lake were only three or four miles 

 north from the head of the Lake Fork outlet, and are, so far 

 as the present writer could detect, nowhere much above 960 

 feet, it may be stated with confidence that nothing was found 

 to support the idea of differential uplift. 



The limits of the lake, shown in the accompanying map, are 

 such as it seems to have had at the highest stage. They are 

 nearly coincident with the 960-foot contour of the topographic 

 sheets, the only notable exception being near Craigton, where 

 the bars reach 967 to 968 feet. Around much of its shore the 

 limits are marked by a sandy strip and by a change from a 

 smooth to a slightly undulating surface. The shore features 

 generally, however, are very faint. The deepest part of the 

 bed of Craigton Lake, under the present conditions of filling, 

 is between 940 and 945 feet. Much of the lake bed has solid 

 ground at a level above 940 feet, the amount of peat} 7 growth 

 being usually, as shown by ditches, only five or six feet. The 

 lake bed was probably filled somewhat by sediment brought in 

 by glacial streams from the receding ice sheet. The volume 

 of water discharged from the lake is likely to have been much 

 greater than that of the present drainage through Lake Fork 

 because of this relation to the melting ice sheet. The per- 

 sistence of the lake after the diversion to the Lake Fork outlet 

 would be measured by the time involved in cutting the outlet 

 channel about fifteen feet deeper, and this, it is thought, should 

 have been accomplished in a relatively short time, perhaps 

 before the ice had melted away from the headwaters of this 

 drainage system. 



On page 448 of Professor Hubbard's paper, attention is 

 directed to a typographical error in an earlier paper that made 



