124 College of Forestry 
on a filled arm or bay of Tully Lake proper. Devil’s Dye-tub 
bog is taken to be the last vestige of this former bay, which 
as the land was built up above the shallower waters became 
isolated, undrained, unaerated, sour (?) toxic (7%) deficient 
in certain plant nutrients —in short became, if not an ex- 
treme type, still a fairly typical bog. Note the attendant 
circumstances : 
(1) A small cireular pond some scores of feet in diameter 
of typically dark bog water without a vestige of larger aquatic 
vegetation.’ This is so nearly filled that in dry midsummer 
the oozy, uncompacted organic substratum lies partly exposed 
to the air. 
(2) A floating Sphagnum-sedge zone encroaching upon the 
open water. 
(3) An invasion of heath shrub (leather leaf, bog rosemary 
and Labrador tea) into the sedge zone with thickening of the 
Sphagnum mat. The substratum still floating at high water 
stages but generally more firm. 
(4) Next outside these a circular zone of tamarack. 
(5) The occurrence of such characteristic bog species as 
snake-mouth (Pogonia ophtoglossoides |L.| Ker.), pitcher 
showed clear marl at twenty-two feet but the solid bottom was not 
reached. In the water-lily zone near shore and in one foot of water 
the marl depth was twelve feet to hard bottom. In the swamp forest 
one hundred feet from the lake shore, one foot of black muck was under- 
laid by ten feet of marl. This marl deposit (in every respect like 
that in the lake bottom) shallowed out to less than two feet in depth 
on the dividing ridge between the lake-arm basin and the dye-tub 
basin, then on the dye-tub side increased rapidly to four, eight, ten feet 
in thickness, but as the test stations approached the center of the basin 
or bog proper, a deposit of brown fibrous peat from one to ten or more 
feet in depth lay above the marl. The final test station lay at the 
outer margin of the tamarack zone and perhaps one hundred fifty feet 
from the “dye tub.” Here with ten feet of brown peat and thirteen 
feet of marl with peat fragments, the sampler failed to reach solid 
bottom. Indeed, it would still sink slowly by its own weight. I have 
no doubt that further tests will show more than thirty feet of filling 
in the dye-tub basin and that the adjacent arm of the lake will show as 
much as fifteen feet of filling —marl—under the present pondweed 
vegetation. 
1 The occurrence of a slimy layer of blue-green alge has been noted on 
the submerged ooze. 
