ARMCHAIR GEOLOGY ON THE CONTINENTAL DIVIDE

The writer's 1967 Ohio Journal of Science article on an anomalous drainage pattern based solely on observation of topographic maps involved armchair geology. The same approach (albeit enhanced by subsurface geology) was employed in studying the drainage basin of lakes in an expanse of glacial outwash in west-central Minnesota's Otter Tail County. Major outflow is northward from Clitherall Lake by a stream and a long zone of seepage, from the east end of which the drainage divide extends around the lake's northeast end, across a region of outwash, and up a ridge of till to a peak (western Minnesota's highest) 9 miles ESE of the lake, where it becomes the continental divide (Hudson Bay/Gulf of Mexico). It winds westerly back into the outwash region to Belmont Lake (elev. 1348'), which drains toward Crane Lake (1338'), which empties into Clitherall Lake (1336'). From Belmont Lake a prominent ridge extending westward to northwestward is the “official continental divide” (OCD) in governmental publications. However, topographic maps show that ponds and lakes higher than 1336' occur only on the OCD and its flanks. Others in a region of over 15 square miles are lower and define a main water table sloping toward the OCD. Its gradient continues into and beyond the OCD in some areas. Water on the OCD's northern to eastern side must join that of the main water table to travel back beneath the ridge whence it came, via a drainage system the details of which are beyond the scope of armchair geology. The real continental divide seems to include ridges near the western shores of all three lakes plus stretches of shoreline seepage into the Gulf watershed on Belmont (southern), Crane (northwestern), and Clitherall (southern and western). It then extends northwestward to a high ridge west of West Battle Lake.