322 ANNUAL OF SCIENTIFIC DISCOVERY. 



feet of strata, from the greatly altered shale, or fire-clay, immediately be- 

 neath the trap, through the successive slates and coke-seauis to the un- 

 changed bituminous coal at the bottom of the section. 



EXTENSIVE DEPOSIT OF GYPSUM. 



Dr. Shumard, who accompanied Capt. Marcy in his reconnoissance of 

 the head waters of the Red River, thus describes an immense deposit of 

 gypsum in that territory : 



This field is probably the largest in the world, and extends from the 

 Wichita Mountains to within a short distance of the nearest Mexican 

 province. Throughout its entire extent the gypsum presents itself to the 

 surface in such a manner as to be very easily worked, and is of the purest 

 quality. Not unfrequently we travelled for miles over continuous beds, 

 which, from their snowy whiteness, and the great abundance of glittering 

 selenite (transparent gypsum) they contained, added greatly to the interest 

 of the scenery ; while here and there immense bluffs often several miles 

 in extent, and thickly capped with the same material projected to the 

 height of two or three hundred feet above the level of the surrounding 

 country. In many places it was observed to be twenty feet in thickness. 



* 



DISCOVERIES IN THE OLD RED SANDSTONE. 



During the past season some highly interesting discoveries have been 

 made in the Lower Old Red Sandstone beds of Thurso and Wick, in 

 Scotland. Fossil wood and shells, the existence of which in Caithness 

 was hitherto unknown, have been abundantly found in situ, the former 

 at Thurso, and both wood and shells at Wick and in the vicinity, the 

 shells having undergone considerable abrasion. These are facts extremely 

 interesting to geologists, and will doubtless give new life to the explorers 

 of the Old Red Sandstone formation, bestowing, as they do, positive evi- 

 dence of what has formerly been considered at best but doubtful the 

 existence of vegetable organisms of the land at the Old Red period. 



ON THE WATERS OF THE GREAT SALT LAKE, ROCKY MOUNTAINS, 



By Dr. L. D. Gale, (Stansburg's Expedition to the Great Salt Lake, 

 Philadelphia, 1852.) Amount of solid contents, 22.422 per cent. Spe- 

 cific gravity, 1.170. Composition : 



Chloride of sodium, ....*. 20.196 



Sulphate of soda, 1.834 



Chloride of magnesium, ..... 0.252 



Chloride of calcium, trace. 



