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gradual slope, where the frozen lake bottom was shoved up the incline and left as a 

 thin mantle upon the melting of the ice; (2) along an abrupt shore, were ice ridges 

 were heaped up and bowlders from the lake bottom carried to heights of several feet 

 above lake level, and in places the banks of the lake greatly disturbed; (3) at the 

 head of bays occupied by mud, marl, and weeds, where the rampart has the shape of 

 a more or less symmetrical fold. The folds are on the lakeward side of the shore 

 where banks are abrupt, and on the landward side where they are very gradual, and 

 on both sides where lakeward and landward conditions were balanced. In some cases 

 a series of folds resembling the Appalachian Mountain structure was developed, fea- 

 tures of which are noted below (in reviewing Van Rise's discussion). 



The changes involved in the production of the ramparts are summarized as 

 follows: (i) Beginning of freezing process. (2) Ice over the lake and temperature 

 falling, ice thickens below and raises upper surface, setting up tensile stresses and 

 producing surface cracks. The cracks receive water from below which freezes. Cracks 

 open repeatedly until lowest temperature is reached, when the ice is approximately 

 adjusted to the size of the lake basin at minimum temperature. (3) The temperature 

 rises, compressive stresses are set up, and relief comes either through forming ridges 

 in the ice or ramparts along the shore. Cracks also form from the under surface. 

 (4) Freezing temperature, the water wells up into the cracks and freezes, and again 

 the ice-sheet becomes a solid mass adjusted to the size of the basin, and the cycle of 

 changes is completed. 



In the discussion of this paper (pp. 158-62 of volume cited) Van Hise calls 

 attention to analogies which the ice phenomena present to the crustal deformation of 

 the earth, among which are noted: (i) the manner in which normal folds pass into 

 overturned folds ; (2) the successive development of folds ; (3) the elevation of anti- 

 clines more than the depression of synclines; (4) the formation of folds at right angles 

 to each other; (5) the combination of folds and faults; (6) the forcing of water up 

 through cracks by the pressure exerted by synclines. The force acting upon the 

 earth's crust is gravitative stress which comes from various causes, including changes 

 in temperature, which is the controlling cause of ice ramparts. 



Collie, George L. Wisconsin Shore of Lake Superior. Bull. Geol. Soc. 

 Am., Vol. XII, pp. 197-216, igoi. 



The paper deals with the shore phenomena of Chequamegon Bay and the Apostle 

 Islands. These islands, it is thought, have resulted from the drowning of preglacial 

 valleys. The strong topographic features of the mainland were produced in pre- 

 glacial time, but glacial deposits have produced a marked influence on the topography. 



Changes in lake level are found to involve a rise, now going on, as well as the 

 lowering from high levels of glacial lakes that once occupied this lake basin. The 

 recent rise is shown by two lines of evidence: (i) The lower courses of the streams 

 tributary to the lake are drowned through the incursion of the lake water ; (2) certain 

 shore features, such as bars and spits, are in process of rapid destruction. The lake 

 bars, island spits, tombolos, beaches (platform, barrier, cliff, and storm), shoals, 

 lagoon and marsh, deposits, are considered, and also features produced by wave 

 erosion, such as caverns, coves, cliffs, benches, and stacks. The last mentioned are 

 small portions of rock cut off from the parent cliff through the action of waves in 

 opening and enlarging the joint planes. 



