MEDINA SANDSTONE. 



71 



8. MEDINA SANDSTONE. 

 Red Sandstone of Oswego, Niagara Sandstone of the Reports. Saliferous Rock of Eaton. 

 . . (No. 5. Pennsylyania Survey.) 



10. • 



This rock succeeds to the grey sandstone, no define^ Iwie of division existing between them. 

 In this rock we find, the Fucoides harlani, the fossil- figured in the above wood-cut, and in 

 none other of the whole of the New- York system has it been seen. It appears, therefore, to 

 be one of those fossils which are limited to a rock, and which affords us a positive character 

 whereby to recognize the rock or its position in the great series. The observations in New- 

 York have been fully confirmed by similar ones ip Pennsylvania. There this fossil appears 

 in the same position, and in sandstone of like diversity of character as to color, etc., as. in 

 New-York generally. It is abundant on the Juiiiata, and on the west branch of the Susque- 

 hannah. I first found this remarkable fossil in. Virginia, about fifteen years ago, near the top 

 of Flat-top mountain, a little to the west of the Salt valley above Abingdon. It was in white 

 sandstone, which caps that mountain, and which rests upon a red sandstone reposing upon a 

 grey or olive calcareous sandstone containing numerous testaceous fossils, referable rather to 

 those of the sandstone shale of Pulaski, than to any other part of the New- York system. 

 These facts are given to show the confidence which may be placed in certain species of 

 fossils, as a character to determine the position of a rock. 



This sandstone is almost invariably of a red color, generally a brown red, more rarely 

 variegated light red and yellowish, and in a few rare instances a light or whitish color par- 

 tially greenish. It is both fine grained and coarse grained, the latter usually of the deepest 



