QUATERNARY DEPOSITS, 
215 
74 . 
Shows a series of the same large arching and folds, and angular movements. 
The above wood-cuts were copied from the drawings of Mr. Amsden, formerly an assistant 
engineer of the Black River canal, who kindly offered his services to give a transcript in 
miniature of the forms assumed by those disturbed layers. The engravings show three dis¬ 
tinct parts : First, in the descending order, the sand which covers the clay deposit; under 
which is a range of undisturbed layers or thin beds of clay, resting upon the series of dis¬ 
turbed ones, the object for which the engravings are given ; these in their turn, being placed 
upon a second range of undisturbed beds, which form the bottom of the feeder. The disturb¬ 
ed beds or layers are placed between two perfectly undisturbed ranges ; showing the various 
forms of curvature, contortion, plication, wrinkles or folded axes, by which such appearances 
have been named. These disturbances extend for a considerable distance along the feeder, 
though of but little thickness. The beds both below and above the contorted ones, are per¬ 
fectly undisturbed throughout their whole course, as represented in the engravings ; but the 
disturbed layers do not possess this uniformity, for they exhibit portions that are undisturbed. 
When the disturbed portions are compared with the undisturbed ones of the same layer, they 
show that the former were raised, greater space being required by the layer where contorted 
than where undisturbed. These interesting forms of disturbance were no doubt the result of 
unequal, local and lateral pressure, which the nature of the country admits ; for such forces 
must have operated when the immense mass of alluvial which once covered all that part of 
the valley where the Black river now flows, was swept away. 
