Vol. 58. ] PHYSICAL DEVELOPMENT OF DOMINICA, ETC. 349 
In front of Grand Savanna, the lower 20 feet of the bluffs are 
composed of yellowish gravel and sand showing wave-action, with 
some larger boulders. Upon the denuded surface of this deposit is 
another, of grey gravel, with some angular materials. ‘This upper 
deposit, which has a thickness of 30 feet, may be called the Grand 
Savanna Series. It is succeeded by a homogeneous, vertically 
ointed, earthy deposit 15 feet thick. : 
Immediately north of Coullibistre, at the end of a mountain-spur, 
is a gravel composed of coarse and fine material showing wave- 
action ; it includes some boulders 10) feet in diameter. Occupying 
denuded hollows in its surface is a coral-formation. The gravels 
were seen to an elevation of 200 feet; they belong to the lower 
series, as at Morne Daniel. The beds undulate and dip in various 
directions from horizontal to 15° or 20°, showing variable disturb- 
ances of the strata. The respective ages of the gravels will be 
considered after describing the coral-formation. 
VI. On tHe Corat-Pornt FoRMATION AND THE AGE 
OF THE GRAVELS. 
Occupying the little valleys, upon the surface of the gravels at the 
base of Morne Daniel, is a whitish marl, more or less filled with 
corals. The base of this coral-bed is 50 feet above the sea, and the 
deposit is 30 feet thick. At Check Hall, a mile to the north, is a 
small terrace, 40 feet high, composed of the same coral-marl. Ata 
point another mile northward, filling a little valley about 50 feet 
wide, is a recurrence of thisformation. In all these places the coral- 
bed rests upon denuded surfaces of gravel. So also the marl, made 
_ up of fragments of mechanical limestones, with some fossil remains, 
at Coullibistre, with a thickness of 30 feet, rests in the hollows of 
the gravels. The white marls sometimes become grey, from the 
admixture of volcanic sands or ashes: they also contain pebbles 
and boulders. The scattered fragments of this calcareous formation 
show its former extension, and the enormous denudation to which it 
has subsequently been subjected. 
I obtained the following collections, the corals of which were 
kindly determined for me by Dr. T. Wayland Vaughan and the 
mollusca by Mr. Charles T. Simpson. Some echinoids also were 
found. 
CorALs, 
Orbicella cavernosa, Linn. Siderastrea siderea, Ell. & Sol. 
O. acropora, Linn. Lsopora muricata, Linn., forma pal- 
Colpophyllia gyrosa, Ell. & Sol. mata, Lam. 
Mo.uvsca. 
Venus cancellata, Linn. Pecten sp., seems to be identical with 
V. paphia, Linn. subnodosus, Sow., found only on the 
Cardium subelongatum, Sow. (?). western side of Tropical Amevica. 
Lucina awrantia, Desh. (?). Pecten sp., 8 to 10 inches in diameter, 
Glycimeris pectinata, Lam. could not. be extracted from the 
Gl. undata, Lam. rock. There is no species of this 
Lutricola interstriata, Say. size now living in the adjacent sea. 
Tellina interrupta, Wood. 
