RECENT AND FOSSIL RIPPLE-MARK. 
49 
with the sea. If, as my observations on land and marine ripple- 
mark appear to indicate, the symmetrical type is generally found 
on lake bottoms and the asymmetrical type on sea bottoms the 
first named type of ripple-mark should greatly predominate in the 
sandstones of the Joggins section. The ripple-mark beds of 
this section were carefully examined twice along the series of 
beds extending from the old grindstone quarry to the cliffs 
southwest of the Joggins mines. Many horizons of finely 
preserved ripple-mark occur in this famous section (Plates 
XXV B and XXXII). All of those observed are, with one excep- 
tion, of the symmetrical type. One slab which had fallen from the 
cliffs near the middle of the section displayed the asymmetrical 
type of ripple-mark, probably representing either current action 
under special conditions within a lacustrine area or temporary 
access of marine currents. The evidence of the other ripple-mark 
horizons fully conforms with and corroborates the evidence of the 
fossils in indicating lacustrine origin for the great bulk of the 
sediments of the section. The current marks found in this 
section (Plates XXXI and XXXIII) occur below the Coal 
Measure series. 
The Berea sandstone of Ohio is another terrane which 
furnishes in its abundantly ripple-marked beds important evidence 
regarding their history (Plate XXVII) . With reference to the type 
of ripple-mark characterizing these beds Hyde writes 1 : “The ripples 
are entirely (so far as observed) of the oscillation (symmetrical) 
type, that is, formed by the slight forward-and-back motion of 
the water which is caused by the passage of a wave. Not a 
single occurrence has been noticed which suggests typical 
‘ripple-drift,’ the type of ripple which is produced by strong 
currents of water moving in one direction. The ripple crests 
are usually from three to five inches apart and rarely reach six 
inches. This interval varies within a few feet on any surface.” 
My own observations which include numerous sections of the 
Berea sandstone between lake Erie and central Kentucky 
coincide with those of Prof. Hyde in noting no exceptions to the 
1 Hyde, Jesae E., “The ripples of the Bedford and Berea formations of central and southern 
Ohio with notea on the palaeogeography of that epoch,” Joum. Geol., vol. XIX, No. 3, 
1911, pp. 262-263, 
