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PROF. J. W. SPENCER ON THE GEOLOGICAL AND [NoV. TQOI, 



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II II 



He includes in this 

 last formation the 

 marls upon the hills, 

 the limestones in 

 the escarpments, and 

 other calcareous ex- 

 posures at lower 

 altitudes. This has 

 j^iven rise to diffi- 

 culty in determining 

 their age : for, upon 

 some of the hills 

 there is an un- 

 conformable marl, 

 much newer than 

 the strata in the 

 escarpments, a fact 

 apparently unno- 

 ticed by him ; and 

 again the beds at 

 low altitudes, con- 

 taining the modern 

 types of organisms, 

 are much more re- 

 cent than the age 

 Avhich he assigns to 

 this formation — 

 the older Pliocene. 

 (Moreau de Jonnes 

 did not regard all 

 of these deposits as 

 so recent.) Prom 

 the fauna of the 

 volcanic sands, and 

 from nearly the 

 same which he 

 found occurring in 

 the lower lime- 

 stones (roches a 

 r a vets), including a 

 Terebratula, Duchas- 

 saing concluded that 

 all the lower beds 

 mentioned belonged 

 to the Miocene 

 Period. 



The fossils in 

 the limestones are 

 poorly preserved, 

 but among the few 



