26 GEOLOGICAL REPORT. [147 



siliceous sandstone, which lias been mentioned as taking the place, occasionally, 

 of the ferruginous sandstone. Where thin ledges (6 to 8 inches) of this rock 

 occur, the surfaces exposed to the weather sometimes show a great number of 

 rounded holes, like gimlet-holes, penetrating the rock at right angles to the strati- 

 fication line ; which is also the direction in which it most readily cleaves. On 

 breaking such blocks we find in the interior of the mass numerous crevices, 

 which I cannot describe better than as resembling those left in burnt brick, when 

 straw or chaff has been used in their manufacture. These crevices are almost 

 always lined with some ferruginous matter, and whenever they reach the surface, 

 the action of the atmosphere soon widens and rounds them. In some instances 

 too I have met with blocks in which these crevices were singularly contorted, in 

 such a manner as would result if green grass leaves were kneaded up with plastic 

 clay, and then burnt out. Whether or not these crevices represent organic 

 remains, it is difficult to decide ; at times it may be thought that the entire form 

 of a blade of grass has been traced, but when followed up, instead of terminating, 

 it may open out into a wide, irregular spa«-e, lined also with ferruginous matter, 

 and from which, perhaps, similar, but utterly irregular fisures radiate in several 

 directions. — It is hardly less difficult to construe them into fucoids. 



47. The characteristics of the Orange Sand formation in Mis- 

 sissippi, as given above, leave little doubt as to the circumstances 

 under which it has been formed. The character of the surface upon 

 which it rests, its own irregular stratification, and the dependence, 

 to a great extent, of the nature of its materials upon that of the 

 underlying formations, proves beyond question that its deposition, 

 preceded and accompanied by extensive denudations, has taken 

 place in flowing water, the effect of whose waves, eddies and 

 countercurrents is plainly recognizable in numerous profiles. Nor 

 can there be any doubt that the general direction of the current 

 was from north to south, although locally changed or directed by 

 the pre-existing inequalities of the surface. 



The arrangement of the pebble-beds into belts (running, in 

 Mississippi, approximately N. and S.) proves that currents of 

 greater velocity, capable of transporting these coarse materials, 

 existed there, coincident in the main with the channels of the great 

 rivers at present existing — the Mississippi and Tombigbee ; the 

 connection of the latter channel with the former, having, it appears, 

 been subsequently closed by the induration into puddingstones, and 

 consequent resistance to denudation, of the pebble-beds of N. E. 

 Mississippi and N. W. Alabama, thus throwing northward the 



