Some Pro-Glacial Lake Shorelines 
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its southern end, by two spits bearing to the east, both of which 
are crossed by the above mentioned highway; north of these 
spits for a distance of about one-quarter mile the shoreline is 
not distinctly recognizable; a cliff marks the remainder of the 
island’s periphery. 
Lake Arkona 
The mapping of the Arkona on this sheet is not final; it is 
known to be incomplete, and there is uncertainty as to some of 
the deposits interpreted as Arkona. 
A submerged beach loses some of its sharpness even when 
initially strong. The ridge suffers from the work of waves and 
currents unless covered by a considerable depth of water; in 
case the transition to the higher stage was effected slowly, there 
was greater modification of the shoreline. However, the local 
discontinuance of a beach does not always mean modification; 
a beach may never have been formed in that place. Along the 
lakes of today, there are stretches where no shoreline features 
are developing. 
West of Sand Hill there are two low segments of sandy beach 
slightly above the 700-foot contour. Near the Castalia-Clyde 
highway, and parallel to the Warren shoreline, are many strips 
of beach, in places above the 690-foot contour and elsewhere a 
little below that altitude according to the topographic sketch- 
ing, which probably represent the Arkona. Another segment is 
mapped southwest of Clyde; wind deposits in this locality have 
rendered the mapping quite indefinite. 
Lake Warren 
The Warren level, throughout the first mile commencing on 
the eastern side of the Bellevue sheet, is indicated by a cliff 
skirting Sand Hill. Lying off-shore, near the margin of the quad- 
rangle and continuous with a ridge on the Sandusky sheet, is 
a low swell of sand, a barrier beach. The cliff slope in the lime- 
stone disappears near the Pennsylvania Railroad, west of which 
is an interval of nearly a mile in which I am unable to find any 
trace of a shoreline. Eight-tenths of a mile directly west of 
Weyers is a sandy area which blends northward into a well 
developed shore ridge, increasing in height toward Castalia. The 
