140 
THE GEOLOGIST. 
must be so much less than above a b that the sand can be left at h c, 
and not drifted forward beyond c. When such is the relative velocity 
of the current before and after arriving at b, the particles of sand are 
drifted along the bottom from a to h, and thrown down on the slope 
6 c at an angle of from 30° to 40°, varying according to the character 
of the material. We may often see beds of this kind in the pi'ocess 
of being formed in rivers and water-courses, and can clearly perceive 
that the current must come from the opposite quarter to that towards 
which the beds parallel to 6 c dip. When the water is all dried up, 
and especially in frosty weather, when the otherwise loose sand is con- 
solidated with ice, it is easy, by cutting into small beds of this kind 
of structure, to see the smaller bands of varying colour and character 
parallel to b c, represented by the lines in fig. 1, and to perceive that 
it is identical with much of the so-called " false-bedding." Since, 
however, some false-bedding has been produced in a very different 
manner, it is desirable to distinguish that just described by a special 
name, and I have therefore employed the term " drift-bedding," in 
allusion to its being formed by the drifting forward of the material, 
and to its being so pre-eminently characteristic of deposits drifted 
into their present resting-places, and not in anywise deposited from 
above, as in the case of other kinds of stratification. False stratifi- 
cation may also have been produced under a variety of circumstances, 
differing from those just described ; but in many cases, as when, for 
instance, a single bed, as in fig. 1, extends with uniform thickness and 
character for several hundred yards, all other explanations are out of 
question. 
Strictly speaking, perfectly developed drift-bedding and simple 
horizontal stratification are two extreme structures which gradually 
pass into each other. In drift-bedding the material is drifted forward 
along the bottom a h, and thrown down on b c, whilst none is 
deposited on a 6 or c e. On the contrary, where simple horizontal 
stratification is formed, none is washed forward along the bottom, but 
all is deposited from above, more or less uniformly, from a to e. The 
connecting link between these is the "grained and striped stratifica- 
tion." In passing into this, the angle bed becomes gradually less, 
the velocity of the current above a b and c e becomes more and more 
nearly equal, the sand is di-ifted over the face of the inclined plane b c, 
