•[33] DECAYED PEBBLES — CRETACEOUS FOSSILS. 1& 



pebble bed is of inconsiderable thickness, beneath it lie beds of yellow and pink 

 sands, down to the water level. 



The pebbles thrown out of wells and gravel pits in this region contain a great 

 variety of rocks in the fresh state ; among these, hornstone of various tints, agate, 

 chalcedony, lydite with white veins, rock crystal, and hard standstone ; in the 

 former three, impressions of palaeozoic fossils, and chalcedonized corals, are 

 common ; also oolitic pebbles of the same materials. Mixed with these fresh 

 pebbles there are others consisting in the main of a white or yellowish, light, 

 porous, siliceous mass, whose particles appear crystalline under the microscope ; 

 Avhich adheres to the tongue, is often readily broken by hand, yet bears most 

 unequivocally the several characteristics of the rocks constituting the fresh 

 pebbles, (except the rock crystal). The structure of the agates, with their 

 crinoidal columns, the chalcedonized corals, the oolitic pebbles are there ; so are 

 the veined lydite and hornstone, with the substance of the vein usually unchanged ; 

 so that we sometimes find vein skeletons of such pebbles, from which the soft 

 silica has been removed by water. Nor are the two extreme conditions alone 

 found ; every degree of transition from fresh agate to the amorphous mass, may 

 be traced ; some pebbles are changed outside, but fresh in the interior ; in others., 

 an incipient dullness of the surface announces the commencement of the process. 

 Whatsoever may be the nature of the latter, it is evident that one of its results 

 must have been the formation of a siliceous solution, which percolated down- 

 wards. It appears therefore that in these pebbles, we see the product of the 

 beginning of the process of which the silicified wood marks the end. 



I have not ascertained what is the particular stratigraphical relation of these 

 decayed pebbles to those in a fresh condition. The only peculiarity of the 

 country which might have some bearing on these phenomana, is the great pervi- 

 ousness of the soil, in consecpience of which, most of the hollows are without, 

 ajwater channel, and semi-cylindric in shape. — I have observed similar pebbles in 

 other localities, though not often with equal frequency. 



33. Cietaceous Fossils in the Orange Sand. — I have found well 

 defined cretaceous fossils in three distinct localities ; in all of these 

 they occur in ferruginous sandrock on the summits of high ridges ~ r 

 the calcareous material of which the corresponding cretaceous 

 strata consist, has been changed into a ferruginous sandstone not 

 differing, apparently, from that ordinarily found, but in all cases 

 of a conglomeratic character, and full of rosettes and irregular 

 galls of yellow ochre and brown hematite. 



One of the localities mentioned is near Harris' Cut, on the Memphis and Charles- 

 ton Eailroad, S. 3, T. 3, E. 9, E., Tishomingo county, (if 27.) Fossils are quite 

 numerous, but badly preserved. Those identified are the following : 

 Cucullaea capax, Con. 

 Qervillia ensiformis, Con. 

 Dosinia densata, Con ? 

 Cardiinn Tippanum, Con ! 



