278 
FLORIDA STATE GEOLOGICAL SURVEY. 
“there is a thinning out of the strata eastward and northward and a 
deepening of accumulation toward the west and south.” Langdon 
(1. c. p. 323) had previously estimated the rate of dip of the formations 
overlying the Chattahoochee limestone at about twenty-six feet per 
mile. Langdon does not state, however, specifically that a similar rate 
of dip applies to the limestone, although such inference is perhaps im¬ 
plied. Foerste assumed (1. c. p. 54) for the Chattahoochee a slope 
of about nine feet per mile. Harris (1. c. p. 58) estimates the dip in 
the strata from the north end of Aspalaga Bluff to Rock Bluff, at an 
average of twenty-three feet per mile. 
In determining the rate of dip the effect of the folds in the strata 
must be taken into consideration. This is especially true of estimates 
made through short distances. The rocks at the Chattahoochee Land¬ 
ing section were found to dip northeast at a rate roughly estimated at 
176 feet per mile. The dip of the strata through short distances in 
the direction north of northeast in the cuts along the Atlantic Coast 
Line Railroad northeast of River Junction was found to be approxi¬ 
mately 100 feet per mile. Along the face of Aspalaga Bluff the change 
of level in the strata can be measured in the direction south of west 
to north of east. In this section a change of level of at least as much as 
thirty feet per mile may be observed. In all these sections the rapid 
dip is accounted for as previously explained by the presence of numer¬ 
ous small anticlines and synclines. To determine even approximately 
the average dip it is necessary that the level of a single stratum should 
be determined through a considerable distance. Stratum No. 2 of the 
Aspalaga section is very characteristic lithologically and cannot be 
confused with any other stratum of that section, certainly not with 
any stratum lying above it. Followed toward the north this stratum 
is seen occasionally along the side of the bluff at successively greater 
elevations above the river. Three miles southwest of River Junction 
the top of this stratum lies, according to an approximate measure¬ 
ment, about thirty-five to forty feet above the river level (stage of 
March 5, 1909.) At Chattahoochee Landing calcareous clays sim¬ 
ilar in character occur as high as eighty-five feet above the river. 
Chattahoochee Bluff and Aspalaga Bluff are distant in a direct line 
seven miles. Since in the Aspalaga section the calcareous clays 
lie fifteen to nineteen feet above the river and calcareous clays of 
this character are found at no higher level in this section, the dip of 
this stratum in the direction south of southwest is believed to be at 
least fifty feet and possibly more in a distance of seven miles, 1 or 
1 The fall of the river which amounts to between one-half and one foot per 
mile if allowed for will slightly increase the estimated rate of dip in this and 
the following measurements. 
