200 R T. Hill— Tertiary and luh , 



maceoas earths. Under the microscope this material is found 

 to be largely composed of siliceous remains of minute Radio- 

 larians. It is distinctly stratified, and contains occasional 

 thin layers of a gray blue clay, and some secondary flint, in 

 the form of nodules. It has clearly undergone great dis- 

 turbance, as shown by the vertical arrangement of its beds, 

 and apparently lies below the yellow beds, which are Miocene. 

 The reservoir for the village water works is located upon the 

 single hill where it outcrops on the southwest side of the har- 

 bor. The beds are over 500 feet in thickness; and I think 

 they overlie the oldest of the limestones, but could not ascer- 

 tain this with certainty. Neither this material nor the yellow 

 beds which together constitute at least 500 feet of the Ter- 

 tiary series, can be classified as of coral-reef origin. 



In many places the Tertiary beds are distinctly stratified, as 

 seen in the Castillo Principe plateau west of Havana, where 

 they contain alternations of stratified argillaceous layers. Like- 

 wise at Matanzas, the older limestones exhibit every character 

 of sedimentary deposition with molluscan remains, rather 

 than of coral reef growth. At Baracoa, ISTuevitas and else- 

 where on the west coast the limestones are not only strati- 

 fied, but they alternate with Miocene argillaceous and arenace- 

 ous beds of a yellow material, containing great numbers of 

 molluscan fossils. In fact, I do not believe that any of the Ter- 

 tiary limestones are of reef rock origin, but they are mostly 

 organic and chemically derived marine sediments mixed with 

 the calcareous debris of the life of the ocean's slopes, and 

 rarely with an almost imperceptible proportion of the finer 

 detrital sediments of the local land. 



While these limestones and alternating beds have a great 

 areal extent it would be a mistake to assign to them a propor- 

 tionate thickness ; accurate measurements will not make their 

 thickness anywhere greater than 1000 feet. I estimated from 

 the dips in the Rio Armendaris section that it was there from 

 800 to 1000 feet ; the incomplete section in the canon of the 

 Yumuri of Matanzas reveals 800 feet ; the canon of the Yu- 

 muri of Baracoa shows 600 feet; the summit of Junki dis- 

 plays less than 1000 feet ; while the section from 14 kilome- 

 ters south of Havana to Batabano is not over 1000 feet. In 

 fact, these limestones may be said to constitute a comparatively 

 thin veneering over the old metamorphic floor. 



The old limestone formations occur from end to end of the 

 island and extend in many places completely across it down to 

 the water level. Their continuity is interrupted only by ero- 

 sion in spots along the central region. Only the low coast 

 adjacent to the sea level is covered by later deposits. De 

 Castro's geologic map of Cuba has, in an excellent manner, 



