AUG. 19, 1923 VAUGHAN: STRATIGRAPHY OF THE VIRGIN ISLANDS 305 
depth is over 1,000 fathoms. ‘The maximum altitude in Saint Croix 
is 1,164 feet, the top of Mount Eagle. The higher land is dissected and 
has gradual slopes similar to those mentioned for the islands on the 
Virgin Bank, but Saint Croix is peculiar in that in its southwestern 
part there is an extensive, gently sloping limestone plain. The shore 
line features are indicative of submergence as in the case of the other 
islands. 
STRATIGRAPHY 
In the Virgin Islands three major sets of rocks may be recognized’ 
as follows: (1) Upper Cretaceous sediments and interbedded volcanic 
tuffs, breccias, and lava flows; (2) Post-Cretaceous, probably early 
Tertiary, intrusive gabbro, dolerite, diorite, and quartz-diorite, and 
perhaps also volcanic extrusions; ; (3) Oligocene and Miocene marls 
and limestones. 
Upper Cretaceous Rocks 
Saint Croix 
The older rocks of Saint Croix are exposed in the northwestern part 
of the island and they occupy the entire area east of Christiansted. 
They comprise sandstone, shale, and limestone, with interbedded 
voleanic tuffs. A very instructive exposure may be studied at 
Waiter’s Point. On the east side of this point there are thinly bedded 
sandstone and shale, west of which is limestone interbedded with 
voleanic tuff. Quin published notes on the exposure at this place 
and collected Cretaceous fossils there, but he did not know the biologic 
affinities of the fossils or their geologic significance. The Misses 
Quin presented to me, for transfer to the United States National 
Museum, all of their father’s collection and I collected an additional 
species. Dr. T. W. Stanton supplies the following list of species 
from Saint Croix: 
Inoceramus sp., related to I. proximus Tuomey. 
Barrettia monilifera Woodward. 
Barrettia sparcilirata Whitfield? 
Radiolites nicholasi Whitfield. 
Caprinula gigantea Whitfield? 
Caprinella occidentalis Whitfield. 
There is no room for doubt as to the geologic age of the deposits 
from which these fossils come—it is Upper Cretaceous. 
The interbedding of voleanic tuff with the limestone has been 
mentioned. 
