11 The American Geologist. January, 1894 
It is possible, however, thai successive layers of coarse and 
of fine sediment may be produced at a very great angle with 
tile actual bedding plane and with the surface of the water. 
This false bedding is formed under peculiar circumstances; 
and the first condition i< identical wit 1 1 thai necessary for the 
true bedding which it simulates, namely, deposition in a cur- 
rent. Bui in the true bedding, in order to produce alternat- 
ing deposits, differing in size of material, a current of vary- 
ing speed is required; while the false bedding is well-formed 
only in a current of nearly constant velocity. 
Ln St. Louis county, northeastern Minnesota, about two 
miles south of Iron Junction on the Duluth. Missabe & North- 
ern railroad, a cut in a level plain of sand and gravel shows n 
section a hundred yards long and fifteen or twenty feet high. 
The stratification appears to be well marked. At a distance, 
the layers are seen to dip steeply north; and even within a 
few yards this seems to be the true bedding, marked through- 
out the greater part of the section. Indeed, were it not for 
the peculiarity of such stratification in drift deposits, it 
might be passed by without suspicion. Close inspection re- 
veals in places the real lines of stratification, often faint and 
sometimes difficult to distinguish. These are, in their gen- 
eral course, nearly horizontal, and their outline is that char- 
acteristic of ripple-marks. 
Ripple-marks are often seen in the sandy bottom of shallow 
streams. As has often been pointed out, they present a mod- 
erately sloping surface, as that of greatest resistance, to the 
current: while the leeward side is steep. It was in a shallow 
glacial stream, therefore, that this deposit was laid down. 
When it was formed the precipitation of sediment was 
going on rapidly. Thus the material, once formed into ripple- 
marks, was not disturbed and rearranged for the slow forward 
movement of the ridge with the current, as in regions of slow 
deposition: but was quickly covered up with new layers. 
Yet the deposition was not so rapid but that the surface al- 
ways preserved the ripple-marked structure. 
As each fresh layer was deposited upon the bottom, the 
most of it came to rest on the steeper, or sheltered, side of the 
ripple-marks. Thus, in the figure, if the original surface be 
represented by a, the new layer will assume the position 6, the 
