As no census of the Republic has ever been taken and data relative to births and deaths have not been collected regularly, it is not possible to compile statistics as to the death rate in the various provinces. The data so far available seem to indicate that the healthiest province is Puerto Plata, followed by Santiago, Azua and Monte Cristi, after which come Santo Domingo, La Vega, Espaillat, Pacificador, Samana and Barahona. The mortality rate is highest in the province of Macoris where the annual number of deaths is reported to average about thirty per thousand.
The most frequent endemic diseases are malaria which is to be feared near marshes and stagnant waters, pulmonary consumption, which, however, is not more common than in the United States, and diseases of the digestive organs. Yellow fever is unknown and the sporadic cases which have occurred were due to the importation of the disease from other countries. The only epidemic in recent years occurred in Puerto Plata in 1901 when ten deaths were recorded.
The hookworm disease is very prevalent, but its ravages are not so apparent as in certain other tropical countries. Venereal diseases are exceedingly common. Evidences of the presence of leprosy and elephantiasis are occasionally seen. The measures taken for the segregation of lepers are far from thorough; the lepers' asylum of Santo Domingo City is situated inside the city walls and is surrounded by habitations of the poor. Cases of typhoid fever are sometimes registered during the hot spell, from July to October, but the victims are usually foreigners who have been careless of climatic requirements. The foreigner who will observe temperance and prudence in all things, who will be careful of what he eats and drinks, who will avoid exposure to rain showers, or to drafts when in perspiration, will easily become acclimated. Realizing that many tropical disorders originate in a foul stomach, the natives upon the slightest provocation have recourse to a purgative, and the custom is one which the stranger should not hesitate to adopt.
CHAPTER IX
GEOLOGY AND MINERALS
Rock formation.—Mineral deposits.—Gold.—Copper.—Iron.-Coal.—Silver.—Salt—Building stone.—Petroleum.—Mineral springs.—Earthquakes.
The geological formation and the mineral wealth of the Dominican Republic have never been thoroughly studied, in part because of the physical difficulties and in part as a result of the civil dissensions. The government has never had money to spare for such objects, and private investigators have suffered much hardship and lost many days in opening paths through tangled underbrush, and in crossing rugged mountain ranges in uninhabited regions. The physical obstacles and the necessarily superficial examination consequent thereon may explain the contradictions of detail in different reports. About the middle of the nineteenth century several studies were published, and three scientists who accompanied the American Commission of Inquiry in the year 1871 made a report on geological conditions.
From such studies as have been published it appears that the rock formations of Santo Domingo correspond to the secondary, the lower and middle tertiary and the quaternary epoch. The most ancient part of the island is the central mountain range, also a series of protuberances in the Samana peninsula, the nucleus of the Baboruco mountains and a single point in the northern coast range near Puerto Plata. The tertiary lands are those forming the entire northern part of the island from the central range to the sea, portions of the Samana peninsula between the older rocks, a large area to the southwest of the Zamba hills, smaller tracts between the Jaina and Nizao rivers, and the region between the salt lakes on the Haitian frontier and between Barahona and Neiba. The modern lands are the coast plains and the small terraces on the south of the central range and on the south of the Baboruco mountains, the Maguana, Azua and Neiba valleys, small areas on the north coast at the foot of the mountains, and the marshes and Yuna River delta at the head of Samana Bay.
In the central mountain range is found a nucleus of eruptive rocks which have raised and twisted sedimentary strata, covering them and forcing them aside. This nucleus is not a regular feature of the whole length of the chain, but is an irregular mass beginning about at the middle, in the region of the Jaina River, and extending in a series of parallel lines obliquely across the backbone of the range to the border of the Republic and on into Haiti. Among these rocks and bent and broken by them are the slates, conglomerates and calcareous rocks which are found in the mountains and over the whole surface of the island. The character of the central range and the inclination of the strata of cretaceous rocks make it probable that the island emerged from the sea in the eocene period, its area being then confined to the extent of the central mountain chain, with a few small islands to the south, one or more islets to the northeast, comprising the older peaks of the Samana range, and a small archipelago to the southeast, where the hills of Seibo now are. During the miocene period these islands became surrounded with coral reefs, the vestiges of which remain in strips of calcareous rock found in the same position in which they were deposited. Towards the end of the tertiary period, after a time of quiet, there was a new rise of the land. While the hills to the south of Samana Bay and the bed of the Cibao Valley from Samana Bay to Monte Cristi rose slowly, there was an upheaval further to the north, and the Monte Cristi Range was formed. Before this period it had been a bar at sea-level, covered with a clayey sediment of chalk. At a later geological period the great plains to the north and east of Santo Domingo City were formed.
Traces of valuable minerals are so general in the Republic that it is said there is hardly a commune where a more or less abundant mineral deposit is not found. The exceptions are the lands of recent coralline formation, such as the municipality of San Pedro de Macoris and the southern portion of the commune of Higuey.