TRANSACTIONS OF THE SECTIONS. 631 



dip and deviation of the strata are lilvc those of all the other 

 strata towards the hills; and though, in particular localities, they 

 do not lie altogether conformably to the coal-measxu-es, yet, on 

 the whole, they may be said to be conformable ; and in some 

 places, as will immediately be seen, they are actually overlaid 

 by the coal-measures. In these beds of soft blue clay numer- 

 ous strata of sandstone are seen, but not of any great thickness 

 or running to any extent. They are commonly wedge-shaped, 

 and thin away to nothing. These imbedded masses of sand- 

 stone very commonly contain, nay, sometimes are entirely com- 

 posed of, accumulations of small conglomerate, containing num- 

 bers of pebbles, vegetable impressions, and even fossil remains, 

 in curious and interesting confusion. This conglomerate not 

 unfrequently is highly ferruginous. It was in the latter kind 

 that Lord Greenock discovered an entire tooth and the remains 

 of others. This tooth has been described in the Edinburgh 

 Philosophical Journal. It was sent to London, and submitted 

 to the inspection of Mr. Clift ; but Dr. Grant has since more 

 minutely examined it, and particularly its internal parts, which 

 were not seen by Mr. Clift, and he is decidedly of opinion that 

 it is a tooth of the Lophius piscatorius, or sea devil, and further, 

 to use his own words, that it " has been preserved to us precisely 

 as it fell from the jaw upon the loose sand." 



Besides these imbedded sandstones there is, in this marl for- 

 mation, a yellowish calcareous and cellular rock, which has all 

 the appearance and many of the properties of magnesian lime- 

 stone. This rock is seen on the banks of the Tweed, princi- 

 pally near Coldstream : the strata are thin, none of them exceed- 

 ing a foot in thickness. It is not, however, only on the banks 

 of the Tweed that this mineral has been found ; it is associated 

 in a beautifully crystallized state with the Scremerston seam 

 of coal woi-ked near Berwick, and even in some parts is blended 

 with the coal so as to render the latter impure, and in a great 

 measure unfit for sale. This limestone has been analysed, and, 

 out of 100 parts, found to contain 50 of carbonate of lime, 44 

 of magnesia, 4 of silica, and 1'2 of peroxide of iron. The spe- 

 cimen analysed was from Birgham Haugh. In beds of dark 

 blue clay or shale, immediately in the vicinity of these strata of 

 magnesian limestone, nodules of iron ore occur, though far less 

 pure and genuine than generally occurs in the coal-fields. 



Another mineral of occasional occurrence in the marl-forma- 

 tion is gypsum. There are three kinds, red and white gypsum 

 in veins intersecting the clay beds of blue marl ; and selenite, 

 which fills vip the cracks and interstices of the marl beds, where 

 they are exposed to the air. 



