124 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 13, NO. 7 
rocks are greatly altered near the contacts. Dacite porphyry in the 
Montagnes Noires may be of the same age. 
In the Terre-Neuve district stocks of Quartz diorite were intruded 
into the old lavas and the Eocene limestone probably during Miocene 
time. ‘This intrusion has a direct bearing on the genesis of the ore 
deposits of the Terre-Neuve district. 
At the end of middle Oligocene time there were flows of nephelite 
basalt, an unusual type of rock in the West Indies, in the mountains 
between the Cul-de-Sac Plain and the Artibonite Valley. 
Several hundred specimens of igneous rocks were collected. Chemi- 
cal analyses have been made of 5 specimens. 
Tectonics.—During late Mesozoic and Tertiary time the West 
Indian region was part of the great equatorial geosyncline that appar- 
ently almost completely encircled the globe. In the Republic of 
Haiti, as in other parts of the geosyncline, the Mesozoic and Tertiary 
rocks were crumpled during the Alpine period of folding. One of the 
surprising results of the reconnaissance is the discovery that the tec- 
tonic features of so large a part of the Republic are due to folding and 
crumpling of the rocks during and at the end of Miocene time. The 
Montagnes Noires, the Chaine des Mateux, and its prolongation east- 
ward to the Dominican border, are anticlinal arches formed at the 
end of Miocene time. The Central Plain, Artibonite Valley and Cul- 
de-Sac Plain are deep synclinal troughs of the same age. Miocene 
beds are involved in the folding in the Northwest Peninsula. Many 
of these mountain ranges and troughs are bordered by high-angle 
thrust faults. A zone of imbricated high-angle thrust faults is well 
exposed along the southern border of the Cul-de-Sac Plain. Similar 
thrust faults were found along the northern border of the plain, show- 
ing that this trough is not a down-faulted block, bounded by normal 
faults, as had previously been supposed. Marine Miocene beds 
underlying an interior lowland in the Commune of Jérémie are now 
separated from the sea by a high range composed of limestone of 
upper Eocene age. Lignite-bearing beds of Miocene age at Camp 
Perrin are thrust northward and are separated from the Cayes Plain 
by a range of upper Eocene limestone probably thrust northward. 
The results of the folding at the end of Miocene time are most appar- 
ent in the central part of the Republic, which was very mobile during 
most of Tertiary time and where a great thickness of Oligocene and 
Miocene deposits were laid down. The movements continued into 
Pliocene time, as marine Pliocene beds near Jacmel are crumpled. 
— eel 
