316 ANNUAL OF SCIENTIFIC DISCOVERY. 



markings which usually accompany them, over that of the "ripple markings," 

 so generally appealed to by geologists as the signs of the ancient water levels 

 or sea-margins of the globe. Explaining, in accordance with the suggestions 

 of Babbage, how these latter may be produced under deep water, by the elastic 

 undulation of the fluid molding the movable sediments into wave-like grooves 

 and ridges, having the semblance of the ripple transmitted to the bottom of 

 shallow waters by the wind, he showed how easily this appearance in the 

 strata may lead geologists to erroneous inferences as to prolonged subsidences 

 of the earth's crust where the phenomenon abounds. The footprints of birds 

 and reptiles on the rocks give evidence which is less fallacious, for they 

 indicate, without any ambiguity, that they were impressed in marine or tidal 

 strata, while these were yet moist, and were intermittingly exposed, wet, to 

 the air, and covered up. They are, therefore, among our best records of the 

 ancient water levels of the continents. 



NEW FOSSILS FROM THE SANDSTONES OF THE CONNECTICUT 



VALLEY. 



The position of the sandstones of the Connecticut valley is of much interest 

 to the geologist, and has never been positively determined. This is mainly 

 owing to the fact that with the exception of the footmarks, very few well- 

 characterized fossils have been discovered in this formation. 



Mr. Edward Hitchcock, Jr., in a communication to "Silliman's Journal" de- 

 scribes a fossil fern found in the sandstone of Mount Tom, near Easthampton, 

 Mass., which seems without doubt to belong to the genus Clathropteris of 

 Brongniart. Previous to this discovery several specimens of this genus had 

 been found, and are now in the cabinet of Amherst College, but none so well 

 defined as to indicate the genus to which they now seem undoubtedly to be- 

 long. Brongniart regarded this fern as very characteristic of the Lias sand- 

 stone. 



The specimen in question was found in a coarse reddish sandstone, in the 

 west face of Mount Tom. The upper part of this mountain is trap, beneath 

 which the sandstone crops out with an easterly dip of about 25. The sand- 

 stone has a south-easterly dip accross the whole of the Connecticut valley. 

 That east of this trap range is made up of finer materials and is of a more 

 slaty character than that on the west. The place where this fern occurs is 

 somewhat west of the middle of the valley. President Hitchcock has lately 

 found by measurement that the thickness of the sandstone east of Mount 

 Tom is more than 8000 feet, and that on the west, or below Mount Tom, is 

 nearly 5000 feet. Supposing one half of this thickness to be accounted for 

 by original deposition on an inclined surface, there will still remain a thick- 

 ness of some thousands of feet both above and below the locality of the fern. 

 A thickness equally great, for the sandstone of the Connecticut valley was 

 found in measuring another section, across the valley at Turner's Falls, thirty 

 miles north of Easthampton. It appears therefore to be certain that a species 

 of Clathropteris occurs in the sandstone of the Connecticut valley not far 

 from its center, measuring across the strata, and near to the interstratified 



