122 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 13, NO. 7 
Miocene rocks, consisting principally of conglomerate, sandstone, 
siltstone and marl, floor the Central Plain, the Artibonite Valley and 
other lowlands. Crumpled Miocene rocks extend along the southern 
edge of the Cul-de-Sac Plain and are exposed in road cuts and ravines 
near Port-au-Prince. A preliminary account of the Miocene beds 
of the Central Plain has already been published.* Copies of this 
report may be obtained by applying to the Engineer-in-Chief of the 
Republic of Haiti. The Miocene rocks in the Central Plain were 
studied in greater detail than those of any other region, and extensive 
series of fossils were collected. ‘The Thomonde formation, one of the 
divisions of the Miocene beds, contains a molluscan fauna of more 
than 300 species, in addition to Foraminifera, corals, and Bryozoa. 
A limestone at the base of the overlying Las Cahobas formation con- 
tains a large number of reef corals. Other collections of Miocene 
corals and mollusks were obtained at many localities in the Artibonite 
Valley and elsewhere. A description of unusual specimens of Orthau- 
lax aguadillensis Maury, one of the most striking and common mol- 
lusks in the Thomonde formation, is awaiting publication.‘ 
Marine rocks of Pliocene age were found in the valley of Riviere 
Gauche and in nearby regions near Jacmel. An interesting fauna of 
corals and mollusks was obtained from these beds. Flood-plain 
deposits, called the Hinche formation, cover extensive areas in the 
Central Plain. These and similar beds in other lowlands may be of 
Pliocene age. 
Marine Pleistocene deposits, consisting principally of coral reef 
rock and coralliferous limestone, were discovered in many parts of 
the Republic. They are most extensive in the western part of the 
Northwest Peninsula, where they cover the Bombardopolis Plateau 
and the magnificent emerged terraces that lead down from the plateau 
to the sea like gigantic stairs. In this part of the Republic these 
Pleistocene rocks are at an altitude of 400 meters above sea, level. 
Pleistocene coral reefs were found in the Cul-de-Sac Plain, especially 
along the southern border of Etang Saumatre. Pleistocene flood 
plain deposits are common in the lowlands. 
More than 300 collections of fossils were obtained from the Creta- 
ceous, Tertiary, and Pleistocene rocks, including Foraminifera, corals, 
crinoid stems, Echini, Bryozoa, brachiopods, mollusks, ostracods, 
® Woodring, W. P., Stratigraphy, structure, and possible oil resources of the Miocene 
rocks of the Central Plain: Rep. Haiti Geol. Survey, 19 pp., map, 1922. 
4 Woodring, W. P., Tertiary mollusks of the genus Orthaulax from the Republic of 
Haiti, Porto Rico, and Cuba: Proc. U. 8. Nat. Mus. (in press). 
