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whole island was sunken to the abysmal depths.

      During the upper Oligocene time very nearly the whole island was undoubtedly submerged. Previous to this volcanic agencies had been very active throughout the larger portion of the island. Mountain building in Oriente had begun before the deposition of upper Oligocene strata, and the Sierra Maestra had already been elevated to a considerable height above the sea. It is probable that the sea at this time covered the whole of the island, with the exception of portions of Oriente province along its north and south coast, and occasional high peaks along the axis of the provinces further west.

      The Miocene period was one of general uplift. The whole of the island as we at present know it, was above the level of the ocean's waters. There were foldings and uplifts during this period, and volcanic elevation along the axial line being greater than at the sides. It is probable that the folding of the Oligocene strata noted in the vicinity of Havana and Matanzas took place during this time. It may be inferred that the central portion of the province of Oriente was more highly elevated than the coastal portions, since upper Oligocene limestones occur in this section at considerably higher elevations than along either the north or south coast.

      It is furthermore very probable that the terracing of the Oligocene coral reefs, such as may be seen in the vicinity of the city of Santiago, was taking place during that time. All the evidence goes to show that these are wave-cut terraces. It may be added here that all of the elevated Pleistocene coral reefs recorded are plastered on the surface of the upper Oligocene formations, or in some instances older geologic rocks. This applies to every later coral terrace that has been described, beginning with Cabanas and extending entirely around the island to the City of Santiago.

      The existence of marine Pliocene in Cuba has not been proved. There may be pliocene rocks in the vicinity of Havana some 60 feet above the sea level. If these are true Pliocene, it would indicate a subsidence during that time of from ISO to 180 feet. The character of the fauna found in the quarry on Calle Infanta does not indicate a greater depth than from SO to 70 feet for the water in which the limestone was deposited.

      Subsequent to this deposition, there was an elevation which caused the land to stand some forty or fifty feet higher than it does to-day. This probably took place in early Pleistocene times, at which time the Isle of Pines and Cuba were connected. One reason for the belief in this elevation is the existence of an old, deep and comparatively narrow cut in the bed of the present channel leading out of Havana harbor. There is further evidence of a general elevation found in borings for water, three miles southeast of the city of Santiago.

      At a depth of some 70 feet below the sea level, in the Rio San Juan Valley, stream-carried pebbles were found. This would indicate that the bottom of this valley once stood at least 70 feet or more above sea level. Subsequent to this elevation, there was a subsidence varying from 40 to 70 feet. There were doubtless other slight oscillations during the Pleistocene period, and these may be going on at the present time, although we have no evidence from records of actually measured monuments established since the Spanish occupation of the island.

      Paleontologic, biologic and physiographic research seems to indicate that there has been no land connection between Cuba and North America at any time since the beginning of the Tertiary, unless perhaps during the Oligocene period, and it seems probable there was no connection whatever during cretaceous times.

      Cuba furnishes a very interesting field, not only for geologic research, but for a far more extended study and survey of its many important mineral zones both for scientific and for economic reasons.

      Topographically the surface of Cuba may be divided into five rather distinct zones, three of which are essentially mountainous. The first includes the entire eastern third of the province of Oriente, together with the greater part of its coast line, where the highest mountains of the island are found. The second includes the greater part of the province of Camaguey, made up of gently rolling plains broken by occasional hills or low mountains, that along the northern coast, and again in the southeast center of the province, rise to a height of approximately 1,500 feet above the general level.

      The next is a mountainous district including the greater part of eastern Santa Clara. The fourth comprises the western portion of this province together with all of Matanzas and Havana. The surface of this middle section is largely made up of rolling plains, broken here and there by hills that rise a few hundred feet above the sea level.

      The fifth includes the province of Pinar del Rio, the northern half of which is traversed from one end to the other by several more or less parallel ranges of sierras, with mean altitudes ranging from 1,000 to 2,000 feet, leaving the southern half of the province a flat plain, into which, along its northern edge, project spurs and foot hills of the main range.

      The highest mountains of Cuba are located in the province of Oriente, where their general elevation is somewhat higher than that of the Allegheny or eastern ranges of the United States. The mountainous area of this province is greater than that of the combined mountain areas of all other parts of the island. The mountains occur in groups, composed of different kinds of rock, and have diverse structures, more or less connected with one another.

      The principal range is the Sierra Maestra, extending from Cabo Cruz to the Bay of Guantanamo, forty miles east of Santiago. This chain is continuous and of fairly uniform altitude, with the exception of a break in the vicinity of Santiago where the wide basin of Santiago Bay cuts across the main trend of the range. The highest peak of the island is known as Turquino, located near the middle of the Sierra Maestra, and reaching an altitude of 8,642 feet.

      The hills back of Santiago Bay, separating it from the Valley of the Cauto, are similar in structure to the northern foothills of the main sierra. In the western part of the range, the mountains rise abruptly from the depths of the Caribbean Sea, but near the City of Santiago, and to the eastward, they are separated from the ocean by a narrow coastal plain, very much dissected. The streams which traverse it occupy valleys several hundred feet in depth, while the remnants of the plateau appear in the tops of the hills.

      East of Guantanamo Bay there are mountains which are structurally distinct from the Sierra Maestra, and these continue to Cape Maysi, the eastern terminus of Cuba. To the west they rise abruptly from the ocean bed, but further east they are bordered by terraced foothills. Towards the north they continue straight across the island as features of bold relief, connecting with the rugged Cuchillas of Baracoa, and with "El Yunque" lying to the southwest.

      Extending west from this eastern mass are high plateaus and mesas that form the northern side of the great amphitheatre which drains into Guantanamo Bay. Much of this section, when raised from the sea, was probably a great elevated plain, cut up and eroded through the ages since the seismic uplift that caused its birth.

      The most prominent feature of the northern mountains of Oriente Province, west of "El Yunque," is the range comprising the Sierras Cristal and Nipe. These extend east and west, but are separated into several distinct masses by the Rio Sagua, and the Rio Mayari, which break through and empty into harbors on the north coast. The high country south of these ranges has the character of a deeply dissected plateau, the upper stratum of which is limestone.

      The character of the surface would indicate that nearly all the mountains of the eastern part of Oriente have been carved through erosion of centuries from a high plateau, the summits of which are found in "El Yunque" near Baracoa, and other flat topped mountains within the drainage basins of the Mayari and the Sagua rivers. The flat summits of the Sierra Nipe are probably remnants of the same great uplift.

      Below this level are other benches or broad plateaus, the two most prominent occurring respectively at 1,500 and 2,000 feet above sea level. The highest summits rise to an altitude of 2,800 or 3,000 feet. The 2,000 foot plateau of the Sierra Nipe alone includes an area estimated at not less than 40 square miles. It would seem that these elevated plateaus with their rich soils might be utilized for the production of wheat, and some of the northern fruits that require a cooler temperature than that found in other parts of Cuba.

      In the province of Oriente, the various mountain groups form two marginal ranges, which merge in the east, and diverge toward the west. The southern range is far more continuous, while the northern is composed of irregular groups separated by

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