234 APPENDIX. 



sometimes a little yellowish, in which case it resembles in 

 texture, color, &c., the finer varieties of Muscovado sugar. 

 The loose texture of the rock is, probably, the cause of its 

 presenting but few indications of stratification. The rock 

 which we have just described rests upon a slaty limestone, 

 which has a striped aspect ; the stripes or zones are curved. 

 This limestone appears to be very argillaceous, and is a little 

 softer than the preceding ; its structure is quite earthy ; it 

 effervesces strongly in nitric acid ; its color is a light yellow. 

 The thickness of this bed is about ten feet. Below this, 

 another stratum of limestone is found, w^hich imbeds small 

 black pebbles of quartz, and assumes, therefore, in a slight 

 degree, the character of a pudding-stone, or conglomerate. 

 Its grain is more crystaUine than that of the preceding 

 stratum. It is filled with small cavities, probably the result 

 of a contraction during the consoHdation of the mass. Its 

 color varies from a bluish to a yellowish-grey. This stratum 

 is about seven feet thick. It rises but four feet above the 

 level of the water, and the only rock visible under it is another 

 variety of limestone, which differs from the preceding, inas- 

 much as its grain is much finer and its texture more earthy. 

 It is only visible for four feet. The bed of the river appears 

 to be excavated near the fort in this stratum of limestone. 

 Neither of these limestone formations, under the sandstone, 

 contains any traces of organic remains. If we consider the 

 three inferior beds of limestone as being modifications of the 

 same formation, as we, doubtless, ought to do, then we shall 

 find this bluff to be composed of three different formations — 

 a superior one of lime, with abundant impressions of shells in 

 one of its beds ; an intermediate one of sandstone ; and an 

 inferior, calcareous formation, without any organic remains. 

 The latter certainly bears some resemblance to the limestone 



