MacMUlan: OCCURRENCE OF sphagnum atolls. 9 



without outlets, but distinct beach lines show that since the re- 

 cession of the ice of the Glacial period they have been raised 

 nearly 25 feet above the present level of Devil's lake, being 

 then confluent, with an outlet from the southwestern area of 

 Stump lake, southward to the Sheyenne. 



Devil's lake shows evidence of having attained about the year 

 1830, a level sixteen feet higher than its low stage in 1889, 

 reaching at or near the former date to the line that limits the 

 large and dense timber of its bordering groves. Below that 

 line are only smaller and scattered trees, of which Captain E. 

 E. Heerman informed me that the largest found by him and cut 

 a few years ago had fifty-seven rings of annual growth. Within 

 the twenty- five years since the building of Port Totten, this 

 lake has fallen nine or ten feet; and it has fluctuated four feet, 

 under the influence of the changes in the average precipitation 

 of rain and snow during the past dozen years. 



It is also known that these lakes have stood continuously 

 lower than now, at least by several feet, during a long period, 

 sufficient for the growth of large forests on the shores of Stump 

 lake, and of the north and south Washington lakes and lake 

 Coe, in T. 149, R. 63, for this is proved by submerged logs and 

 stumps, the latter standing rooted in the soil where they grew. 

 Many of these logs and stumps have been hauled out of the 

 southeastern bay of Stump lake by the neighboring farmers 

 for use as fuel. This prolonged epoch of comparative desicca- 

 tion may have coincided with the more arid conditions in the 

 Great Basin, which as shown by Professor I. C. Russell, ap- 

 pear to have entirely dried up Pyramid, Winnemucca and other 

 lakes of Nevada about three hundred years ago."* 



From the case of Stump lake an analogy may be derived for 

 the ponds in Cass county where the atolls have been noted. It 

 is probable, however, that no such lapse of years need be de- 

 manded for the periodic diminution and increase of these 

 ponds, as is indicated by the Stump lake and Devil's lake phe- 

 nomena described above. Indeed, I am not clear that the sud- 

 den rise in the water was not coincident with the completion of 

 the lumbermen's dam across Gull river, the outlet of Gull lake. 

 This I am informed was built about fourteen years ago. By 

 it the level of the water in Gull lake itself has been maintained 

 sometimes as much as eight feet above its original and normal 

 level. It is a question, however, whether the time that has 



» Russell: Geological History of Lake Lahontan, U. S. Geol. Surv. Monog. xi. 

 pp. 223-237, 252. Compare also G. K. Gilbert: Lake Bonneville. Monog 1 p. 25S. 



