90 bulletin: museum of comparative zoology. 



Fossils ^ are generally missing from the Kingston formation ; specu- 

 lation concerning its age must be founded entirely upon stratigraphical 

 relations. In our opinion it is clearly older than the elevated reefs of 

 the Barbican and Hopewell formations of presumable Pleistocene age, 

 and younger than the Bowden formation, being nearly allied by position 

 to the age of the Manchioneal which we consider Pliocene. 



The present beds of both the Hope and the Cobre Rivers deeply 

 indent the Kingston formation, cutting far below the surface of the 

 plain. The alluvium of these stream valleys and their general level 

 constitute distinct deposits which are later described under the head of 

 the Monteiifo formation. 



Tlte Elevated Reefs. — The coast of Jamaica, like many of the other 

 West Indian Islands, is in places bordered by a peculiar formation 

 composed of rocks which were once growing coral reefs similar to those 

 now bordering the island, and wliich have been raised above sea level 

 by general regional elevation in late geologic time. These forma- 

 tions are found in small, limited, interrupted areas in Jamaica immedi- 

 ately adjacent to the coasts, and at altitudes of less than seventy-five 

 feet. They do not have the wide areal development which is seen on 

 the north coast of Cuba, nor do they veneer the higher summits as in 

 Barbados. 



The elevated reef rocks usually constitute horizontal beds of strata 

 from ten to forty feet in thickness. These have a more or less massive 

 exterior, due to surface induration, but when cut into, as they frequently 

 are by the undermining of the sea or in the construction of highways, 

 their interior structure is seen to consist of porous limestone material 

 of varying texture, always more or less minutely honeycombed, and of 

 irregular hardness, with red oxidized spots or yellow patches here and 

 there. They show all degrees of induration, from that of the practically 

 unchanged reef material to firui semi-crystalline white limestones. 



Tljese rocks are composed of coral heads of various sizes embedded in 

 a matrix of marl, — the latter being sometimes indurated into limestone. 

 The licads usually have the erect position which they maintained when 

 they were growing organisms. Some of these are of great size, one 

 specimen, which cati be distinguished in the illustration on Plate XXIX., 

 was six foet in hoiglit. The marl represents the reef debris which is 

 found between tlie growing or dead coral heads of living reefs, and is 



1 Brown, in the .Tatnaican Ixcports, pa;j:o lOt), desoribea a formation similar to 

 that of the Kinjjston in tlio parish of St. Elizabeth alon<i the coast from Alligator 

 Pond Bay to Green Bay, in which remains of huid shells are found. 



