EARLIEE TERTIARY (EOCENE AND OLIGOCENE). 721 



From their usual association with and occurrence above the Montpelier beds, there is httle 

 doubt that they were continuously deposited with the latter and possibly may represent shallow- 

 ing, but nevertheless deep-water beds after the culmination of the Montpelier subsidence. Our 

 knowledge of the upper contact of these beds is very deficient. In Clarendon and St. Elizabeth 

 they clearly occur below the Cobre and Porus (Bowden) formations. 



The name Cobre formation is applied to a local occurrence of white limestone 

 exposed in the canyon of the Cobre. Hill says that from the Bog Walk section it 

 is evident that the Cobre formation lies stratigraphically above the supposed Mon- 

 eague beds at Ewarton and below the May Pen formation. Its relations with the 

 Bowden beds are not established. It apparently occupies an intermediate position 

 between the Moneague and the Bowden. 



For description of the later Tertiary formations, see Chapter XVII (pp. 799-801). 



E-F 15-16. CHIAPAS, GUATEMALA, TABASCO, AND YUCATAN. 



The peninsula of Yucatan is mapped in accordance with an interpretation of 

 the map given by Sapper/'*" who characterizes the Tertiary of the States of Tabasco 

 and Chiapas as follows: 



The major part of the Tertiary terranes consists of marls and shales with sandstones and 

 conglomerates as weU as limestones which are, however, of minor importance. 



The fossils which Sapper cites from these formations are Pecten, Ostrea, Num- 

 mulites, Elypeaster, and different Glossophora (?), lamelUbranchs, and corals. 



Sapper regards these fossils as representing the upper Miocene or some of them 

 as coming from a lower horizon. Dall thinks it probable that they represent the 

 Ohgocene. Sapper further cites certain remains of plants and Foraminifera which 

 were determined by Schwager to be of Tertiary age. 



Heilprin *^^* describes in the following terms the limestone of the Sierra de Yuca- 

 tan, a range of hills which runs in a northwest-southeast line from Ticul in the 

 direction of Peto : 



The rock formation of the Sierra de Yucatan differs in many particulars from that of the 

 basal plain. The surface rock, forming the crest and the slopes on either side — presumably 

 an antichnal structure — is a fairly compact red or reddish hmestone, which seems to rest at 

 nearly all places, as we had occasion to observe in the Caves of Calcehtok and Loltun, on a 

 semicrystalline white or gray marble or on an exceedingly fine grained cream limestone, some- 

 what resembling in texture true hthographic stone. A brecciated Umestone, containing frag- 

 ments of the last-mentioned rock, occurs at intervals along the base of the hills, and we also 

 found it among the rocks used in the construction of the buildings (now ruins) of Labna. I 

 am not absolutely certain as to the age or even as to the general nature of the red rock. The 

 brecciated masses are almost undoubtedly of marine origin, and they give evidence of the 

 encroaches of the sea after the underlying rock had not only been formed but been converted 

 into its present semicrystaUine condition. In other words, the present range of hiUs probably 

 by that time already existed. It is, however, less clear that the red or reddish rock which 

 extends away from the base of the hills but forms their slopes is of marine origin. Its univer- 

 saUty would seem to indicate that it was of this nature, but at manj- places where I examined 

 it, on and off the crests of the hills, it bore suspicious marks of being a disintegration product, 

 which had subsequently undergone cementation. The only fossil that I found in it, on any sur- 

 face exposure, was a Hehx (probably identical with a species now hving in the same region) 

 which was obtained from near the summit of the pass between Ticul and Santa Elena at an 

 48011°— 12 46 



