PORTAGE GROUP. 
233 
sented when a small stream or rivulet, oozing from a cliff or descending a steep hill, becomes 
suddenly frozen. The surface of the ice presents all the inequalities of the flowing water, 
and occasionally little streams have broken through, and flowing a short distance have become 
frozen. Another analogous appearance is to be seen in the cooled cinder from iron furnaces, 
which presents all the inequalities of the first and the congealed streamlets which have flowed 
for a few inches over the surface. 
The woodcut below is a fac simile of a layer of shaly sandstone taken from the bank of the 
Genesee near Portage. There is a thin coating of shaly matter upon the surface, and the 
whole appears to have been moved along while in a semifluid state, either from some force 
applied, or from the inclination of the bed of the ocean. There seems at least no other mode 
of explaining these phenomena. 
101. 
Cast of flowing mud , Portage, N. Y. 
There are several other similar appearances, all varying in some degree; and as we would 
naturally expect, no two localities present precisely the same form of surface. xVTany of them 
appear to have been casts in previous depressions, as if the fluid mud had filled inequalities 
hollowed out by the action of flowing shallow water over a muddy bottom. The ripple- 
[Geol. 4th Dist.] 30 
