1891. J 
327 
[Davis. 
and back to the west for half a mile, when its further extension 
was hidden by woodland. There can be no question of the 
fluviatile origin of this field ; and as stones of similar size and 
form are now found in the bed of the Catskill, it seems warrant- 
able to regard this great spread of cobbles as the work of the 
Catskill at the time when the clays were forming in the Hudson 
trench. If so, the surface of the cobble-field should slant gently 
down stream, and terminate in a steeper descent, the delta 
margin of the stream in the estuary. Moreover, the under strata 
of the cobble-field should be finer ; at a depth of ten or twenty 
feet there should be sand with few pebbles, and below that there 
might even be beds of clay, these being formed early in the 
estuary stage of the valley, before the stream had built its delta 
so far eastward into the quiet waters. Inquiry was made of the 
farmers near by as to the materials under the cobble-field, but 
none of them knew of any cuts or wells by which the deeper 
beds would be revealed. The extension of the cobble-field up 
stream was not examined for lack of time ; but if the interpreta- 
tion here made is correct it should be found continuing at a 
gentle angle of ascent, the angle of the profile of equilibrium of 
the ancient Catskill, when it was well supplied with sand, peb- 
bles, and stones from the recently glaciated slopes of its basin ; 
and as it is likely that this angle is smaller than the slope of the 
preglacial stream-bed, here deeply buried, the upper end of the 
cobble-field should be found where these two sloping lines inter- 
sect. I hope to extend the study of the valley further up stream, 
another season, to determine if this view is correct ; but as it Is 
an essential part of the explanation given, it is here stated, 
though at present only hypothetical. 
About a mile and a half down the road on the left side of the 
Catskill, there is a high level bench of coarse cobbles lying 
against the enclosing slope of the valley. Its height is about 280 
feet. Its surface appeared to slope gently towards the hill-side 
of Hamilton strata. This bench is very narrow at its western 
or up-stream end, and widens to a third of a mile further on, 
where it is cut across by a side stream from the Hamilton hills. 
Its highest bench descends by terrace slopes to several successive 
terrace steps at lower levels, down to about 220 feet above 
tide. The view across the valley to the south is obstructed by 
trees on the outer terrace bank ; but as far as the southern Ham- 
