PALEOZOIC UNDIVIDED. 345 



It is not unusual to meet with varieties, especially the coarse grained, in which the mica 

 is sufficiently abundant as, by the parallelism of its plates, to communicate a laminar and even 

 fissile structure. 



The term quartzite must be understood in this report as implying sUiceous strata, whose 

 matter exhibits no granular structure but is continuous and yet perfectly distinct from vein or 

 segregated quartz. 



Beds of this substance are of common occurrence, generally assuming a vitreous character, 

 but in some instances rather that of hornstone. They are intimately associated with the 

 sandstones and seem occasionally to graduate into the latter. 



Shales, which are also numerous, appear sometimes ferruginous or highly carbonaceous, 

 often associated with mica, and generally soft. * * * 



Calcareous rocks are represented by two varieties in this series, viz, crystalline limestones 

 contained in the slates and alternating with them, and compact limestones, either quite uncon- 

 nected with the schistose group or only associated with its upper strata. The former occur 

 sometimes in massive beds, varying from white to blue in color, often with scattered spangles 

 of sUvery-white mica, and distinguished by decided crystalliae structure. Thinner beds of 

 similar lithological characters, from a few inches to several feet in thickness, exhibit repeated 

 alternations with the, slates or shales. 



Calciferous slates are beds of calcareous base, but with a considerable proportion of earthy 

 matter and a laminar or schistose structure. 



The Caribbean terrane is much folded and sheared. The report cited contains 

 many striking illustrations of the structure. The sequence of the component forma- 

 tions of the group was not satisfactorily made out, and the age, beyond the fact 

 that it is pre-Cretaceous, also remains undetermined. 



D 16. NICABAGTJA AND HONDURAS. 



The pre-Triassic rocks of Honduras are assigned by Mierisch and Sapper to the 

 Paleozoic and are so mapped. Sapper ^^^ states: 



The occurrence of Paleozoic rocks in southern Central America has not been demonstrated 

 with certainty, as it has not been possible to find fossils in the strata. Nevertheless, it appears 

 to be highly probable that there belong to the Paleozoic those rocks which Mierisch assigned to 

 that age, namely, the very steeply dipping limestones, calcareous mica slates, phyUites, clay 

 slates, quartzites, talc, gneisses and amphibolites, talcose and chloritic schists of northeastern 

 Nicaragua; but whether they belong to the Devonian, Silurian, or Cambrian, as Mierisch thought, 

 or may perhaps be of the same age as the Carboniferous terranes of Guatemala, Chiapas, and 

 British Honduras, can not be surmised. According to Mierisch the area covered by these 

 formations in Uli and Uani, as well as in the mining districts of Concepcion and El Dorado, is 

 considerable, although this fact does not appear on his geological map. 



Sapper goes on to mention several localities in Nicaragua and Honduras in 

 which he has observed slates, quartzites, conglomerates, and other rocks which are 

 mapped as Paleozoic, though without any specific evidence. He says : 



In regard to the age of these rocks I can only suggest an inference. It seems to me most 

 likely on grounds of lithologic similarity that these formations are to be assigned to the Paleozoic, 

 along with the slates of the Rio Coco; but it is not impossible that they may be a part, and in 

 that case the lower part, of the Tegucigalpa formation [Triassic]. 



E 19. SANTO DOMINGO AND PORTO RICO. 



Hill *** makes the following statement with regard to Santo Domingo : 



In general, the geology of the island is similar to that of Cuba and Jamaica, more especially 

 the eastern ends,' being composed of four principal formations — -the older mountain rocks, of 



