DABTON.] VIRGINIA. 183 
The horizon of the waters at 130 feet at Franklin, 161 feet at Zuni, 
and 190 feet at Mount Carmel is not certainly known, but it is thought 
to be in the Chesapeake formation considerably above its base. The 
Arringdale well at 75 feet and the Courtland wells at 160 feet are 
doubtfully referred to the basal Chesapeake beds, but the former may 
be down to a lower horizon. 
Basal Chesapeake waters were apparently absent in the North End 
Point, Fort Monroe, Dendron, Claybank, and Gloucester wells. The 
wells at Crisfield, Md., found no appreciable supply of water in the basal 
Chesapeake beds. 
There are several higher horizons of water in the Chesapeake forma- 
tion, and it is believed that the wells at Franklin, Zuni, and Mount 
Carmel draw from Chesapeake beds about 100 feet above the base of 
the formation. The water of the Bowlers Wharf well at 143 feet is 
from about the same horizon, but water reported at 210 feet in the 
Dyiners Creek well is somewhat higher than the others. The water 
beginning at 170 feet at Leonardtown and the waters at 240 and 270 
feet at Coan are from the top of a considerable thickness of sandy 
basal members. 
The salty water at 606 feet at Lambert Point and at 599 feet at Fort 
Monroe, and the ferruginous water at 562 feet at Money Point, all 
near Norfolk, are from somewhat higher horizons. The waters at 140 
feet at Onancock on the eastern shore and at 70 feet at Virginia Beach 
are at still higher horizons. I am not inclined to regard any one of 
these upper Chesapeake horizons as widespread, and with our present 
meager knowledge they can not be predicted with safety. 
As I regard the waters in the Lafayette and Columbia formations to 
be superficial, I secured no data regarding them. 
WELL PROSPECTS BY COUNTIES. 
ALEXANDRIA COUNTY. 
The portion of this county occupied by the Potomac formation is 
underlain by waters which are available in wells of moderate depth, as 
indicated by the success of the wells at Alexandria. 
FAIRFAX COUNTY. 
The portion of this county immediately adjoining the Potomac Biver 
and extending west of the Baltimore and Potomac Bailroad is under- 
lain by water-bearing beds of the Potomac formation. They have only 
been tested by the boring at Sandy Point, near Occoquan Bay, which 
reached the basal waters and passed into bed-rock at 270 feet. At 
Mount Vernon the basal Potomac gravels and sands may be expected 
at a depth of about 350 feet. Possibly water will also be found in 
higher beds. As the dip is quite steep to the east, the depth diminishes 
toward the Baltimore and Potomac Bailroad, where the basal beds 
