Foot-prints of Birds and Impressions of Rain-drops. 395 
Mr. Lyell next visited the red and green shales of Cabotville, north 
of Springfield in Massachusetts, where some of the best Ornithichnites 
have been procured, chiefly in the green shale. The dip of the beds is 
20° to the east, a higher inclination, the author says, than could have 
belonged to a sea-beach. He observed in the same quarries ripple- 
marks as well as casts of cracks, and he was informed that the impres- 
sions of rain-drops have likewise been found. 
In company with Prof. Hitchcock, Mr. Lyell afterwards examined a 
natural section near Smith’s Ferry, on the right bank of the Connecti- 
cut, about eleven miles north of Springfield. The rock consists of thin- 
bedded sandstone with red-colored shale. Some of the flags are dis- 
tinctly ripple-marked, and the dip of the layers on which the Ornithich- 
nites are imprinted, in great abundance, varies from eleven to fifteen 
degrees. Many superimposed beds must have been successively trod- 
den upon, as different sets of tracks are traced through a thickness of 
sandstone exceeding ten feet; and Prof. Hitchcock pointed out to the 
author that some of the beds exposed several yards farther down the 
river, and containing Ornithichnites, would, if prolonged, pass under 
those of the principal locality, and make the entire thickness through- 
out which the impressions prevail, at intervals, perhaps twenty or thirty 
feet. Mr. Lyell, therefore, conceives that a continued subsidence of 
the ground took place during the deposition of the layers on which the 
birds walked. 
It has been suggested, but the opinion has not been adopted by Prof. 
Hitchcock, that the eastward slope of the beds represents that of the 
original beach. With a view to this question, Mr. Lyell examined the 
direction of the ripple-marks, and found that it agreed with the dip, or 
was at right angles to the supposed line of beach; but he adds, though 
this agreement presents a formidable objection to the suggestion above 
alluded to, if the ripples were produced by waves, yet it does not dis- 
prove the opinion, as the ripples do not exceed in dimensions those 
which are produced by sand blown over a muddy beach, and often dis- 
tributed at right angles to the coast-line. Instances of this effect of the 
wind Mr. Lyell has remarked along the shores of Massachusetts. Nev- 
ertheless he is of opinion that the rippled layer of sandstone in question 
contains too much clay to have resulted from blown sand, and he is dis- 
posed to think that in most of these localities the strata have been tilted, 
instances of such disturbance having been pointed out to him by Prof. 
Hitchcock in the state of Massachusetts, and by Dr. Percival near New 
Haven, in Connecticut. In reference to this subject, he says, that a 
few miles from Smith’s Ferry, a conglomerate, several hundred feet 
thick, containing angular and rounded fragments of trap and red sand- 
stone, the base being sometimes a vesicular trap and trap tuff, passes 
