C28. Sisto on the Geology of South Alabama. 359 
But to pursue the details 
the bed, No. 7, which for 
borne section, is e pie: ibited in many other places, and often be- 
comes an important criterion to determine other parts of the 
series. ‘Two miles below, near Forward’s landing, it makes its 
appearance in a similarly i cliff, and becomes quite as in- 
teresting for the abundance of its fossils, with no apparent diver- 
sity of species. And again, still farther down the river, at Bare- 
field’s plantation, it is developed about ten feet above the water, 
in connection with the subjacent oyster 
Four miles farther south, at the bend of the eae near 
limestone creek, the bed, No. 7, appears at low water in con- 
nection with the overlying Claiborne beds. It also occurs in 
the interior of Clark county, where it is exposed in a ravine 
at the base of the white limestone hill; on Limestone creek, near 
the salt works, and at the base of St. Stephen’s bluff one mile 
above the landing : thence in a northeasterly cee its out- 
ceappings may be traced to the borders of Mississ 
all these situations, the stratum under consideration exhibits 
a rothatiaable identity both in its mineral and zoological c¢ 
to the unevenness of the older cretaceous beds which it ‘over-—— 
laps in a tortuous and irregular manner 
e remaining part of the eocene series, exclusive of the su- 
perficial sand and clay, may be included under the 8 et gga of 
white limestone. The peculiarities of this part of the series, 
seem to require such a distinction. It consists of limestone, both 
compact and loose, somewhat arenaceous and marly below, but 
passing upwards into a very pure carbonate of lime, having often 
a white chalky appearance without signs of stratification. But 
the distinction regards more especially its fossils. ‘Though the 
general type of its fauna identifies it as a part of the eocene 
group, yet there is a manifest peculiarity ; the upper portion espe- 
cially consists almost entirely of comminuted remains of marine 
organisms, such as Orbitolites and other coralline forms. Indeed 
the aspect of the species in the subordinate part of the formation 
presents obvious differences, such as occurrences of Echinoderms 
of various genera, pectens and oysters of a peculiar type, and 
above, a very unique species of cetacean mammal. These pecu- 
iarities were, until lately, considered a sufficient reason to class 
these deposits as a newer part of the cretaceous system. t it 
now ascertained both by atigraphical and paleaeeneet ev- 
idence, that they form an ‘upper section of the eocene strata 
We have fixed the commencement of this subdivision ghee 
ately after the bed last considered, No. 7, for here we find an evi- 
dent transition from the prevailing forms of the preceding beds 
