HILL: GEOLOGY OF JAMAICA. Tol 
Mountain Series have great development where they constitute the 
highest mountain summits, the Pico del Yaqui, reaching an altitude 
9f 9,684 foot (2,955 meters) according to Schomburgk. They are also. 
Probably the nucleal material of the Republic of Haiti, and its two 
Westward extending peninsulas. This formation has been described 
dy Gabb! as the Sierra group, and his descriptions in every way 
Coineide with it as it occurs in Jamaica, except that it contains some 
Stavel of different material. 
The occurrence of these rocks in the islands to the east of San 
9mingo is based upon the descriptions given by Cleve in his ex- 
“ellent work on the Northeastern West Indian Islands? He has 
leseribod, as the “ Bluebeache” from St. Thomas, a formation fully 
8,000 feet in thickness consisting of stratified conglomerates and tufls 
largely made up of hornblendic igneous material, which he says also 
Occurs beneath the white limestone formations, on the north side of 
Porto Rico,* and which he considers probably of Cretaceous age. He 
‘as also described the same formation from the Virgin Islands to the 
ĉastward. 
This formation, which is over 5,000 feet in thickness in Jamaica 
"ud 6,000 feet in St. Thomas, is the most important landmark in 
denneken, Gabb, and Tippenhauer present prospective views of the general geology 
Ccessively controverting in a more or less degree the previous observations. 
Gabb’s report on the Geology of San Domingo, notwithstanding its value, 
Presents a confusion of data concerning the Tertiary sequence and the white 
estones in general, very similar to that concerning allied formations in Jamaica. 
a Careful study of the work I am of the opinion that he has failed to interpret 
nou the stratigraphy of these formations. There can be no doubt that he has 
E N Used the two great littorals, the equivalents of the Richmond and Bowden, and 
Wsiflod with the Coast Limestone all the limestone formations from the Mont- 
nt to the elevated reefs inclusive. Furthermore, these errors upon his part 
We led to some very broad generalizations which are utterly untenable. 
an these writers Gabb has given by far the largest and oftenest quoted report, 
le Tippenhauer gives the latest and best general summary (Die Insel Haiti, 
iR, 1898). The recent researches of Bergt, noted on a later page, alleging 
fe sans du an older plesus of Pre-Oretaosous rocks were not pub- 
¿sio at the time of Tippenhauer’s contribution. While Tippenhauer’s age cons 
Nat ul are not always reliable, the sequence which he gives of the rocks is the 
En presentation thereof, and presents a remarkable analogy to the general 
LM sequence as set forth by us, as will be seen by the section on page 172. 
on ata and Geology of San Domingo, p. 83, and unpublished manu- 
UR IM the library of the U. S. Geological Survey. : 
3 pw Svenska Vetenskaps-Akademiens Handlingar, Bandet 9, No. 12, 1870. 
i th ey of the Northeastern West Indian Islands, 1871, p. 4. 
id., pp. 14, 15. 
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