APR. 4, 1923 WOODRING: GEOLOGY OF HAITI 119 
rocks are not close to any known intrusive igneous rocks, and as they 
are so altered by metamorphism, it is believed they may be as old as 
Paleozoic. 
Extensive areas in the northern part of the Republic contain argillites 
of supposed lower Cretaceous age. These sediments were deposited 
principally along the flood plains of streams. Impure marine lime- 
stones, probably of the same age, were found in the southern part of 
the Republic. Upper Cretaceous limestones that contain reefs of the 
peculiar rudistid mollusks found in Jamaica and other West Indian 
islands were discovered in the Arrondissements of Cap-Haitien and 
Grande-Riviére du Nord. 
Rocks of Tertiary age are very widely distributed in the Republic. 
Their succession and their equivalents in the Dominican Republic and 
other regions near by are shown in the table on page 20. The Eo- 
cene and Oligocene rocks are almost exclusively limestones, but the 
Miocene and Pliocene beds consist principally of clastic rocks. The 
Eocene and Oligocene limestones crop out on the crest and flanks of 
the mountains, and the Miocene and Pliocene clastic rocks in the 
plains and lowlands. 
The Eocene is the most extensive series of rocks in the Republic. 
The Plaisance limestone, of middle Eocene age, is confined to the 
northern part of the Republic. It is characterized by undescribed 
species of Foraminifera of the genus Dictyoconus.2. Limestone of upper 
Eocene age is perhaps the most common surface rock in the mountains 
and it has a maximum thickness of more than a thousand meters. 
It contains an extensive foraminiferal fauna, principally orbitoidal 
Foraminifers of the genera Orthophragmina and Lepidocyclina. Upper 
Eocene Foraminifera were collected at about 90 localities. 
Rocks of known lower Oligocene age were not seen during the re- 
connaissance. Middle Oligocene limestones were found in many 
parts of the Republic, particularly in the Montagnes Noires, the 
Chaine des Mateux, and near Jacmel. These rocks are characterized 
by certain species of Lepidocyclina. Limestones of upper Oligocene 
age are extensive around the borders of the Plaine Centrale, in the 
mountains north of Etang Saumatre, south of Gros-Morne, and else- 
where. They contain the foraminiferal genera Lepidocyclina, Nio- 
gypsina, and Sorites, and a fairly large coral fauna. 
2 See Woodring, W. P., Middle Eocene Foraminifera of the genus Dictyoconus from the 
Republic of Haiti: Journ. Washington Acad. Sci., 12: 244-247, 1922. 
