68 Geology of St. Croix. 



to crumble, and the silicious requiring a smart blow of the ham- 

 mer to break them. The grain is uniformly fine. I did not see, 

 in this mass of rock, any thing like a pudding-stone. The form- 

 ation seems to have been deposited in quiet waters, though there 

 are frequent contortions in the strata, which may be due in part 

 to the troubled state of the element from which they were depos- 

 ited ; but probably more to the force by which they were uplifted. 

 There are beds in the ravine near Mount Victory, as we ascend 

 on the road from Sprat Hall, which strongly resemble argillaceous 

 slate. The color of the strata, in other places, passes through all 

 the varieties of brown to that of clay. They are frequently col- 

 ored red by the oxide of iron. 



This is particularly true in the region of Annesley. In such 

 cases, however, the oxide does not appear to have penetrated the 

 substance of the rock, but to have been infiltrated through the 

 seams and crevices. The soil is also impregnated with this sub- 

 stance. 



Thin layers of quartz, from one fourth to half an inch in thick- 

 ness, are often interstratified with this rock, and sometimes cut 

 the regular strata, and also each other, diagonally. Mingled with 

 schistose formations, I often found small beds of marl and calca- 

 reous spar. In some instances, the marl had been introduced 

 from above, in the form of a deposit ; in others, it was obviously 

 interstratified with the rocks when they were formed. The 

 streams, also, which ran down from the mountains over the hard- 

 est rocks, were more or less impregnated with lime. 



I have already intimated, that the strata are often intersected 

 by diagonal cleavage planes. This appeared to me a striking pe- 

 culiarity of the formation. These planes were from one to three 

 inches apart, sometimes parallel, but generally more or less in- 

 clined to each other. They were often crossed by others ; so 

 that the rocks naturally broke into angular, columnar, or rhom- 

 boidal fragments. It was often difficult to distinguish these cleav- 

 age planes from the true lines of stratification. In this respect, I 

 was much struck with the similarity between these rocks and the 

 grey wacke formation of Wales, as described by Mr. Murchison. 



The valleys and ravines of this formation, as I have already 

 said, run in all directions, but more generally in that of the anti- 

 clinal lines of the strata. Such, for example, are those which 

 extend from the coast road, at the west end of the island, towards 

 Jolly Hill, Mount Victory, and New Caledonia. 



