194 RECORD OF DEEP-WELL DRILLING FOR 1905. 
Feet. 
Shale and clay - - 715-72£ 
Sandstone - 725-74C 
Shale and clay 740-742 
Sandstone - - - 743-752 
Shale and clay - - 753-77C 
Sandstone - 770-77C 
Shale and clay. . . : 776-77* 
Sandstone 778-781 
Shale with traces of day 781-796 
Diameter of well, 10, 8, and 6 inches. Water at 265 feet salt, sulphur-bearing, with 
much carbonic-acid gas; unfit for cither boiler or domestic use. Water from the sandstones 
below contained much carbonic-acid gas with 30.22 grains of incrustants to the gallon 
while sodium carbonate and other nonincrusting solids made the water objectionable foi 
boiler use. Flow of well, 19 to 30 gallons per minute; by pumping 150 gallons per minutt 
water is lowered to —346 feet. 
DELAWARE. 
207. Well at Fort Dupont, Newcastle County. 
Well begun December 17. 1904; completed April, 1905. Authority, Capt. L. F. Garrard, jr., construct 
ing quartermaster. Geologic correlations by W. B. Clark.] 
The sands, greensands, and days penetrated by this well are of Pleistocene and Creta- 
ceous age. As a jet rig was used, sonic samples may show a mixture of the particular beds 
penetrated with material washed from strata above. The section is remarkable chieflj 
for the thickness of the Potomac (early or fresh-water Cretaceous) formations. They an 
characterized by red and white clay and sand, as the overlying late or marine Cretaceous 
is characterized by beds of sand containing glauconite, known as greensands. The forma- 
tions, in downward order, are Columbia ( Pleistocene), Rancocas, Monmouth, and Matawai 
(late Cretaceous), Magothy, and Potomac group (early Cretaceous). 
Record of United States well at Fort Dupont. 
Columbia: Feet. 
Yellowish sand and fine gravel, brackish water 0-2^ 
Rancocas : 
Gray, slightly clayey sand and fine gravel 24- 4( 
Dark-greenish limy sand with shells; contains much glauconite 40- 6( 
Monmouth: 
Dark sandy micaceous clay 60-14( 
Medium gray sand with very little glauconite 140-15( 
Brownish-gray sandy clay with some glauconite 160-181 
Mat a wan: 
Dark coarse sand and clay, some glauconite 180-19 1 
Hard, light-red, slightly sandy clay 197-22 
Dark micaceous sandy clay , 223-24 
Fine to medium drab or brownish-gray clayey sand with a little glauconite. . . 2 10-28 
Fine to coarse brownish micaceous clay with some glauconite 280-30 
Magothy, in pari : 
Medium to coarse drab or brownish sand with varying amounts of glauconite 
and occasionally some clay 300-41 
Fine to medium light-gray sand, no clay and very little glauconite 418-4$ I 
Potomac : 
Light brick-red clay with some sand 421 -4( i 
Fine to medium, slightly clayey, pinkish-buff or pinkish-brown sand 467 5( 
Fine to medium brownish-gray micaceous sand ."><)<) 5 .' 
Medium to fine pinkish-brown sand with red and white clay 510-6- ( 
