lo The American Geologist. juiy, lo'^i. 
rock is typical Ix-acli sand and not docp-water material. This 
seems evident from the size and shape of the grains, and from 
the absence of the finer product of trituration in the sand lay- 
ers. The material is .too coarse to be swept far off into deep 
water. 
Abrupt Changes of Material. 
In some sections there arc frequent and sudden changes 
from clear sand to fine clay, as mentioned above, see figure 6, 
plate — . Such abrupt changes do not seem possible in deep 
off-shore waters, but are characteristic of shore deposits. 
Oblique Bedding. 
This is a very common and characteristic structure of the 
sandrock, so common indeed that it spoils a large part of the 
quarry product, and in many openings entirely prevents prof- 
itable working. Figure i, plate II, shows a fair example. 
The old Whitmore quarry, at Lockport, was not w'orked be- 
low a certain plane on account of this structure. 
Ripples, JJ\ri'elines Ete. 
These minor structures, the most common and convincing 
proof of wave work, are exceedingly abundant. No one can 
see the older sidewalks of western New York towns without 
being impressed with the beach origin of the flagging. Wave- 
lines are frequent in great perfection on the smoother flags,, 
while ripples are so common and so regular that the quarry- 
men call them "washboards." Other features, as rill-marks,, 
wind effect, transported shells, etc., are also common. 
Ridges and TrougJis. 
A frequent structure, and the one wdiich suggested the idea 
of "giant ripples," are curving seams, sometimes forming hol- 
lows or upward-facing concavities, sometimes making flat 
arches, and rarely forming crested ridges with slightly con- 
cave sides. Examples of these structures are shown in figures 
I to 8 and 13, plates II, III, IV, V. To the writer there seems 
no reasonable doubt that these structures were produced in the 
process of deposition of the sand. They are not induced or 
secondary features but structural. Thin lamiucC of clayey 
material often make the separating planes. 
