...1.^8 FLORIDA GEOLOGICAL SURVEY—THIRD ANNUAL REPORT. 
tide. The oyster, reef extends about two hundred feet along the 
face of the bluff. 
The unusual thickness of the loose yellow sands at the top of 
the bluff is due to the fact that the upward moving currents of 
air carry sand as it is loosened along the face of the bluff to the 
top where it accumulates as a sand dune. 
Rose’s Bluff also on the Florida side of the river about two 
miles below Crandall is semi-circular in shape and is fully two 
miles long. The following section was made near the middle of 
this bluff: 
Dark colored sand and soil .••.. 4 feet 
Dark iron-stained sand (hardpan) .... 7 feet 
Ochre yellow sand ..,. ... 8 feet 
Sand with some clay ... 5 feet 
Sandy shell bearing marl, blue, oxidizing yellow .............. 4 feet 
Sloping to . waters „ edge at low tide ... 5 feet 
33 feet 
, c. . ' * v : >. > «. - * ,. . . v .. r v " y t • * . v .-a-. at ' - 
. • 1 VA t • .■ - av :. . . , : t Ci| 
AREA OF ARTESIAN FLOW IN NASSAU COUNTY. 
The part of Nassau County in which flowing wells can, be ob¬ 
tained is indicated on the accompanying map by shading. Flow¬ 
ing wells may be obtained as shown by the map, (p. 1-3-5-) m 
approximately the eastern two thirds of the county. A relatively 
small area, including the ridge already mentioned lying near the 
western part of the county and extending north and south parallel 
with the St. Marys River stands too high to obtain flowing wells. 
In this section, however, non-flowing artesian water may be obtain¬ 
ed which will stand within a few feet of the surface. 
LOCAL DETAILS 
CALLAHAN.. 
There are several flowing wells at and in the vicinity of Calla¬ 
han, varying from 410 to 489.7 feet in depth. Three different 
water-bearing strata are reported in all the deeper wells at Callahan, 
the first occurring at about 50, the second at from 160 to 200, and 
the third at 400 to 425 feet. The water from the first stratum 
does not flow but rises to within 6 to 10 feet of the surface, and 
is found in a shell formation. The water from the other two 
strata rises from 28 to 48 feet above the surface. 
The first deep or artesian well at Callahan was drilled in 1904. 
This well was put down at the instance of several of the residents, 
