SECOND ANNUAL REPORT—STRATIGRAPHIC GEOLOGY. 
12.5 
longing to it. DalP has also noted the .fact that the upper beds of 
the Caloosahatchee Pliocene contain a fauna more closely related to 
living forms, than the lowermost layers; and that the shoaling of the 
water permitted the formation of oyster reefs, and, : finally,, the influx 
of fresh water species of Plan orb is, etc. 
StructureThe dip of the Pliocene beds in Florida is usually very 
difficult to determine. The Caloosahatchee River crosses the Caloosa¬ 
hatchee marl at the type locality and thus , affords a good opportunity 
for observing the attitude of the marl beds. Concerning these beds 
Dali says : 1 2 
The uppermost strata .of the Pliocene beds begin to appear above the level 
of the river at low water (during the dry season) about 24 miles due east from 
the shore of Charlotte harbor, and they dip to the eastward out of reach about 30 
miles farther east. Their total measured breadth here is thus at least 30 miles 
and includes the whole of the elevated land between Lake Hickpochee and the 
point on the river , above mentioned. In this distance there are not less than 
twenty visible but very gentle folds of the strata in the direction of the trend 
of the peninsula. 
In a later paper Dali says of these same beds: 3 . 
The Pliocene beds dip gently to the westward so that those portions near 
the sea are newer than those outcropping near the headwaters of the streams. 
In discussing the Miocene the marls near Caloosa were doubt¬ 
fully referred to that period. The Caloosahatchee marl is exposed at 
intervals from near this locality to the vicinity of Labelle, several 
miles farther up stream, where the Pleistocene appears. The fact 
that the Pliocene marls dip beneath the Pleistocene near Labelle may 
be explained by an easterly dip of the beds. The alternative hypothesis 
of a westerly dip would only be true in case the increase in altitude 
of the water surface was somewhat greater than' the thickness ; of the 
Caloosahatchee marl. The actual rise in the water level between these 
localities as determined instrumentally varies with the stage of the 
river, but at mean low water^ is probably less than five feet. Appar¬ 
ently the correct explanation is that the actual dip of these beds is in 
a general easterly direction instead of toward the west. 
Aside from a slight tilting, the marls of the Caloosahatchee River 
have been gently folded so that they exhibit a series of low undula¬ 
tions with axes parallel to the general trend of the peninsula. The 
width of these arches is usually less than one-fourth of a mile; and 
1 Dali, Wm. H., Neocene of North America, U. S. Geol. Survey Bull. No. 84, 
1892, pp. 145-146. 
2 Dali, Wm. H., Neocene of North America, U. S. Geol. Survey Bull. No. 84, 
1892, p. 146. 
3 Dali, Wm. H., Wagner Free Inst. Sci. Trans., vol. iii, pt. 6, 1903, p. 1604. 
