•H)-l The American Geologist. March, 1894 
The ripple-marked lamina generally nearly coincide with one another, 
crest for crest, and trough for trough, except for the slight forward 
movement of each new crest and trough. Figure 1 in the article in the 
January number of the American Geologist expresses this relation of 
the successive lamina 1 , and if other lines were superadded to a. b, and c 
till the whole space of the figure w T ere filled, a very fair idea of the ac- 
tual appearance of the lamination in one of these sandy beds might be 
obtained. 
This structure is best marked where there are no pebbles mixed with 
the sand, for then there are fewer phenomena to obscure it and distract 
the attention. The lines of the growth which each individual ripple- 
mark traces in its onward and upward movement are strongly marked. 
In material of uniform fine sand, weathering brings out this structure 
very strongly, for the looser and more rapidly formed parts which accu- 
mulate on the steeper slope fall away first, leaving the harder parts 
standing out as ridges. In those commoner horizontal beds which are 
of predominating sand, mixed with some coarser material and pebbles, 
the corresponding structure, shown in figure 2 of the above-mentioned 
article, is ordinarily found, providing that the relative proportion of 
sand and gravel is nearly constant, in all the horizons of the bed. This 
structure differs from that in the beds of homogeneous sand only in 
that the loose fine sand becomes mixed with coarser material and oc- 
casionally pebbles. As the pebbles begin to predominate, the false 
bedding, as well as the lamination of the true bedding, tends to become 
obscured and to disappear. 
To sum up, we have in this cut three distinct banded structures, two 
of which are horizontal and the third inclined at a considerable angle. 
The first is a series of thick horizontal beds which differ from one 
another in the average size of material. At a distance this structure is 
very plain, but at close quarters the chances are that it would escape 
observation. The second is a series of finer horizontei layers, consti- 
tuting the ordinary bedding of stratified deposits. This structure is 
best developed in the most sandy beds, and in proportion as the amount 
of coarser material increases it becomes obscured and finally disappears. 
The third is found developed to any noteworthy extent only in those 
beds which were formed with practically the same texture: any change 
in texture destroys the continuity of these layers, and therefore the same 
layer cannot extend from one bed into another. This structure follows 
and marks the linesof growth traced by each point of the horizontal rip- 
ple-marked layers. Each of the larger divisions shows this in a greater 
or less degree, and though the layers are not continuous in the different 
beds, yet they are parallel, and give the impression of a continuous 
stratification. This coarse and steeply inclined striping is, except at 
close quarters, the most striking structural feature in the deposit; but 
when very near, its importance is seen to be slight in beds consisting 
only of sand. 
The first two structures show that the deposit was laid down in sue. 
cessive horizontal layers, and it then follows that the third, which 
