342 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VOL. V. 



marl has been used for some of the beds of White Limestones, as 

 well as for the newer formations, so that it would require further 

 investio^ations to know how much of his marl formation is referable 

 to the Layton series, and how much to the " White Limestones." 

 Perhaps a portion of it may be even more recent. 



The Layton series occurs as a veneer up to elevations of 500 feet. 

 While often not more than ten or twenty feet thick, it may reach 200 

 feet in depth when occupying older valleys which it has partly filled. 



The Layton series is the first formation occurring in Jamaica sub- 

 sequent to the " White Limestone," (Older Miocene). The fossils are 

 few in number and it is not certain that there are any extinct species 

 among, to say the least, predominating modern varieties. The me- 

 chanical character, even where the deposits are mostly composed of 

 marls, may in part account for the common absence of fossils. The 

 denudation following the Layton epoch has in a great measure carried 

 away the formation. Upon the resulting weather-worn country, another 

 mantle also largely mechanical, was laid down. The surface of this 

 latter accumulation has suffered a less degree of erosion than the 

 Layton series, but sufficient to frequently expose the remains of that 

 deposit. 



Comparison of the Layton Series with the Matanzas of Cuba, and the 

 Lafayette of North America, and its Age. — In Cuba the same 

 mechanical marls or limestones occur, containing water-worn peb- 

 bles, and resting upon similar white limestones of old Miocene or 

 Oligocene age, whose surfaces had been greatly eroded. These 

 mechanical marls in Cuba have been designated the Matanzas series* 

 by the writer. The fossils are usually scarce, but they are modern 

 species and quite unlike the Miocene fauna. On the continent the old 

 Miocene accumulations are very much eroded, so that they are often 

 removed from the valleys, and succeeding them (except in Southern 

 Florida), there are the Lafayette red loams and gravels, the latter, where 

 present, usually forming the lower part of the series. The thickness of 

 the whole series, except in the valleys, does not usually exceed twenty 

 feet. This formation so extensively surveyed by Prof. W. J. McGeef 

 occurs over a broad belt of the Atlantic and Gulf states, and the writer 

 has seen it even as far as the southern side of the Gulf of Mexico. In 

 place of being derived from the White Limestones of Jamaica and Cuba 

 (of Tertiary age), the materials of the American Lafayette formation 

 have been derived entirely from the residuum of the decay of rocks of 



* "Geographical Evolution of Cuba," by J. W. Spencer, Bull. Geol, Soc. Am., vol. vii., pp. 67-94, '895- 

 t " The Lafayette Formation,' by W. J. McGee, 12th Rept. U.S. Geol. Surv., pp. 347-522, 1892. 



