LATEE TERTIAEY (MIOCENE AND PLIOOENE). 799 



F-G 12. LOWER CALIFORNIA. 



At Santa Rosalia and Boleo, Lower California/'^ there are deposits of upper Mio- 

 cene age which probably correspond to the beds of Carrizo Creek, California, and 

 which are characterized by Pecten (Plagioctenium) cedroscensis Gabb, Pecten (Peden) 

 carrizoensis Arnold, P. (P.) keepi Arnold, Semele aff. pulchra Sowerby, and Malea 

 aff. ringens Swainson. 



For a general statement of the geology of Lower California and sources of 

 information, see Chapter XV (pp. 644^647) . 



G 14. TAMAULIPAS. 



In the valley of the Rio Bravo, near Matamoros, Tamaulipas, the marine 

 terrane of the late Tertiary is well represented, and according to Aguilera ^^ it is 

 possible to recognize several of Bumble's subdivisions of the later Tertiary of Texas, 

 namely, Oakville, Lapara, and Lagarto. 



H-I 11. TIA JXJANA, LOWER CALIFORNIA. 



At Tia Juana, Lower California,*"* there occurs a formation equivalent to the 

 Purisima formation of California, which belongs at the base of the Pliocene. In the 

 island of Cedros this formation is present but not mapped and is characterized 

 by Pecten(Nodipecten) veatchi Gabb, Pecten lecontei Arnold, and Pecten (Plagioctenium) 

 cedroscensis Gabb. 



E 18. JAMAICA. 



The classification of the geologic formations of Jamaica is given in Chapter XV 

 (p. 640), and the older formations are discussed in Chapters XV and XVI (pp. 639- 

 642, 717-721). 



According to Hill ^^^ the later Tertiary is separated from the early by a hiatus 

 corresponding to the middle Oligocene. The formations representing the late 

 Oligocene or Miocene and the Pliocene are classified as the Bowden, May Pen, 

 Kingston, and Manchioneal formations, in ascending order. 



Under the heading "Bowden and allied formations" (the Yellow limestone 

 of some previous authors), Hill^"^ says: 



This series includes a class of formations which represent the products of events more 

 recent in the history of the Jamaican sequence than those hitherto enumerated. Its members 

 occur around the coastal perimeter of the island, principally along the margins of the sea at 

 altitudes nowhere exceeding 250 feet, and deposited unconformably against the sides of an older 

 mainland. Here and there on the south coast they fill previously formed erosion plains. They 

 were all made during epochs subsequent to an epoch of elevation whereby the white limestones 

 of the Oceanic series and all preceding formations had been elevated into land, had undergone 

 tremendous denudation, and had again suffered partial marginal subsidence. 



They are of four types of formations, to wit, beds of impure marine limestone, gravel, and 

 marl; alluvium of the Kingston type; elevated coral reefs as Olustrated in the Barbican and 

 Hopewell formations; and Httoral deposits of calcareous mud, with embedded fossils of con- 

 temporaneous origin with the elevated reef formation. The four types in their general lithologic 

 characters are analogous to the marine, littoral, alluvial, and coral-reef formations now being 

 made around the margins of Jamaica. 



The Bowden and allied formations of later Tertiary age constitute the older beds of the 

 Coastal series and are aU marginal to the main upland mass of the island. They apparently 



