HILL: GEOLOGY OF JAMAICA. 115 
PART III. 
Paleontology of the Jamaican Sequence. 
Tho entire Jamaican section contains many unfossiliferous horizons. 
N other words, while there are a few zones! where abundant macro- 
Noopie fossils occur in abundanco, a large part of the 10,000 feet of strata 
àro non-fossiliferous. The lower Blue Mountain Series are mostly with- 
Out fossils because of the disturbed conditions during their deposition. 
he Upper portion of the Series is likewise mostly barren, owing to the 
turbulence of the muddy waters in which it was laid down, The deep 
Water Tertiary white limestones, although largely composed of micro- 
“pic organisms, contain vast thicknesses of rock with no macroscopic 
"ganic remains, This is due to the fact that these limestones were 
deposited at great depths, where fossil making forms other than Radio- 
laria were few in number, and the calcareous skeletons of such as did 
exist were dissolved by deep sea waters. 
On tho other hand, the many changes of the character of the habitat, 
uch as the introduction into the sea of the material of the Cretaceous 
Yoleanio outbreaks and changes of level in the later epochs, have inter- 
“Upted the continuous existence of such littoral faunas as leave the most 
"undant remains and which from time to time may have secured foot- 
hold around the island prior to late Oligocene time. Thus it is that 
di few colonies of Upper Cretaceous life which obtained ephemeral 
existence around the margins of the island were deficient in species ; 
1 : i ; y un 
Cambridge forms, a little more diversified, and the Bowden and 
ater y 
t pecies are numerous, as the surrounding seas afforded more con- 
Sant 
and favorable conditions for the life of organisms, 
il * 
* The paleontology of Jamaica is difficult to discuss, because many pre- 
10 1 A i » ; 
"Sly known species have been described from miscellaneous collections 
made by others than the describers) by naturalists who had not visited 
le ig] | 
à and and had no conception of the stratigraphic sequence, position, 
8800] : 
ation, or exact locality of the forms. Such studies are valuable 
O far ; j à ; 
àr as they result in the correct naming of species, but they are too 
Ofte 
N: , oy : 
N accompanied by an unfortnnate duplication of names and conflict- 
o » x i à 
liis Seneralizations and deduetions. "Thus one author referred all the 
kb > 1 . n 
tebrato faunas of the whole Tertiary and later formations, without a 
T 
hese horizons are marked with an asterisk in the columnar section on page 42. 
