206 R. T Hill — Tertiary and later 



tinuity is traceable for many miles, as they rise abruptly from 

 the water's level one above the other in a series of cliffs. On 

 the west end of the island they are not so distinctly visible 

 from any single point of view, for the flat benches are much 

 wider, but they are nevertheless traceable. In other places 

 denudation has destroyed them. 



Besides these benches and terraces whose integrity is dis- 

 tinctly preserved, remnants of older and more denuded plains 

 can be traced. For convenience they may be classified as 

 follows : 



1. The Seboruco or elevated reef plain. ) 



2. Elevated Beach and Cliff lines and > 1. Later terraces. 



the Havana terraces. ) 



3. The Cuchilla plain. ) , .-.,-, 



i rpt t i • i - r 2. Older terraces. 



4. lhe J unki plain. \ 



1. The Seboruco or Elevated Reef plain. — This forms the 

 lowest bench immediately adjacent to the entire north coast 

 and along the Santiago front and is topographically and geo- 

 logically the elevated coral reef. Synchronous with the forma- 

 tion of this beach the elevated playa deposits in the harbors 

 and the elevated cienega or mud deposit on the south side of 

 the Island at Batabanos were made. 



2. The Beach and Cliff Terraces. — On the east end of the 

 island the abrupt north coast is marked by three distinct and 

 abrupt cliffs and terraces cut out of the steep slope of the old 

 600 foot Cuchilla plain or which forms the upland. The three 

 terraces as seen in this region are so clear and distinct that 

 they are readily visible at one view and their continuity is 

 clearly traceable for miles. They are best displayed along the 

 coast adjacent to the mouth of the Yumuri of the east. Here 

 the river empties directly into the sea through a precipitous 

 canon affording a fine cross section of the terraces. The 

 coastal scarp consists of three narrow sub-level benches each 

 surmounted by a vertical cliff. Bench JSTo. 1 is the first sub- 

 level strip above the sea, constituting the present beach. This 

 in general represents the level of the elevated reef which 

 nearly everywhere forms the low lying coastal plain and breaks 

 off at the sea in a surf wall some ten feet in height. Its inte- 

 rior margin against the base of the first great cliff is 40 feet 

 high, and it nowhere exceeds 100 yards in width. 



This lowest, Terrace No. 1, which usually consists of ele- 

 vated reef rock is composed of alluvial gravel immediately off 

 the cut of the river, and a quarter of a mile away to the east- 

 ward it is elevated reef rock. Several smaller beaches make 

 up this lowest terrace, the uppermost of which is the specially 

 well defined alluvial gravel plain. 



