over the New Haven Region. 357 
Maltby Park valley (the central north-and-south depression of 
this border), where the depth is generally from 10 to 20 feet. 
_ (2) The Maltby Park valley has, in general, little till over 
it, the surface being largely one of bare ledges and intervening 
marshy areas. : 
(3) But at one place in the eastern half of this valley (Rd, 
on the map, p. 342) the till has a depth of more than 107 feet; 
and this piling up of till made there the isolated Round Hill (as it 
18 called), and gave it a height of 304 feet above mean tide, 
While the hills of the western border just east and southeast 
are only 140 to 200 feet high. Moreover these hills, and the 
surface along the road south of Round Hill, have not enough 
till to conceal the jagged rocks. ae 
(4) The broadly rounded hills of southern Orange within 
three miles of the Sound, 200 to 280 feet in height, are deeply 
covered with till—the depth in some parts 40 feet or more.* 
Farther from the Sound, the till is usually of less depth, and 
rock-exposures are not uncommon. 
The unusual amount of till and bowlders against the eastern 
declivity of the western border has already received explana- 
ton (p, 348). | 
The existence of bare ledges and little till over the Maltby 
Park valley is evidently a consequence of denudation; the 
region was swept by deep waters from the melting glacier— 
part going southward, directly to the Sound, with a pitch of 30 
feet a mile for the four miles, and the rest northward into the 
valley of West River north of Westville. 
The third feature mentioned is of less obvious gp eestor 
Round Hill stands prominently in view from all directions. 
This isolated feature, its form, and the height of the surround- 
ing region are shown on the following map. The great depth 
of the till at the summit had seemed probable from the fact 
that, unlike the other hills, it has no outeropping rocks over the 
Upper third of its height; but it was proved by an excavation 
for a well made under the orders of Mr. R. M. Burwell, the 
Owner of the place. The well was carried down 107 feet 
through the firmest of stoney and somewhat clayey till before 
Water was obtained, and even at that point rock had not been 
teached. The highest outcrop of rock on the sides of Round 
Hill is at 174 feet above mean tide. 
nother remarkable feature of the region is a deep trench on 
_ the southeast and east sides of the hill, only 118 to 180 feet 
above sea-level, something like the trench around a fortified 
acropolis. 
* On Shi i i st of the region included in the map, 
an saattatig tien edteoenercae 40 feet of “ail; on other hills, several 
Wells go down 20 to 36 feet. 
