no STEPHEN TABER 



Polochie-Lake Izabal Valley in Guatemala, but Powers who 

 has recently visited the region states that he believes these 

 valleys are due to erosion dependent on folding/ Sapper,^ in 

 mapping the tectonic lines of Central America attributes the 

 east-west ranges of Guatemala to folding, and this view has been 

 adopted by other geologists. If the Antillean fault zones continue 

 westward beyond the Gulf of Honduras their curvature is reversed, 

 for in Central America the mountain ranges extend in approximately 

 parallel arcs convex toward the south. 



The Central American ranges, as they approach the Gulf of 

 Honduras, curve gradually toward the northeast, and therefore 

 meet at an angle the north coast of Honduras which extends east 

 and west. Powers states that this coast is evidently a fault-zone 

 area.^ Vaughan correlates the tectonic lines of Honduras with 

 the submarine ridge or plateau connecting the Honduras Peninsula 

 with Jamaica,'^ but this feature is abruptly terminated by the fault 

 scarp north of Jamaica. The tectonic Hues of Central America, 

 according to Sapper, are of several different ages; some having 

 been formed in the Paleozoic, others as late as the Tertiary. Possibly 

 some of these lines continue into the West Indies with curvature 

 convex toward the south while others turn gradually southward 

 and become convex toward the north. Faulting in Central 

 America may have followed along the old structural lines due to 

 folding. The location of Guatemala in a belt of high seismicity 

 that may be traced from the Greater Antilles through Central 

 America and Mexico into California, together with the precipitous 

 topography of the region suggest that the great Antillean fault 

 system may extend into Central America, and, gradually curving 

 toward the north, continue into California. These questions can- 

 not be decided, however, until more field data are available. 



The Sierra de los Organos, which form the backbone of western 

 Cuba, have a northwest-southeast trend and may be genetically 



' Sidney Powers, written communication dated September lo, 1920. 

 ^ Karl- Sapper, op. cit. 



3 Sidney Powers, written communication dated September 10, 1920. 

 ^T. W. Vaughan, "Geologic History of Central America and the West Indies 

 during Cenozoic Time," Bull. Geol. Soc. Amer., Vol. XXIX (1918), p. 618. 



