in the Neighbourhood of Ferrybridge, in 1826-1828. 403 



covered towards Knottingley by the other members of the 

 magnesian formation. But there seems to be a considerable 

 fault or dislocation in the valley of the Aire, which depresses 

 the beds on the north side of that river; so that they have 

 their outcrops further toward the west. 



The fossils which I have observed in this rock in this neigh- 

 bourhood, are the following: 



Axinus obscurus Min. Conch, of various magnitude,common. 



Cardium N.S. one specimen. 



Cucullata N.S. not plentiful. 



Mytilus N.S. This might be mistaken for Gervillia. 



Terebratula ... N.S. Differs from one in Durham, which 

 resembles T, sacculus, Min. Conch. 



Producta perhaps a new species, decidedly unlike 



P. calva, or any other hitherto described 

 from this formation. 



No. 5. — The red blue and yellow clay, with gypsum of dif- 

 ferent sorts, which lies above the yellow magnesian limestone, 

 was cut through in the new canal where the first bridge is 

 thrown over it in Knottingley. We there saw the limestone 

 No. 4. resting upon a layer of yellow clay or marl ; below this 

 a layer of blue clay, and under all the red clay with gypsum. 

 A greater thickness of these beds is exposed in the gypsum quar- 

 ries at Fairburn, on the north side of the Aire. The section 

 at Lord Palmerston's quarry is very instructive, and easily ac- 

 cessible. Diluvial sand and pebbles lie on the surface of about 

 45 feet of the thin bedded limestone No. 4 ; below is yellow 

 clay 2 feet in thickness, then blue clay 6 feet, and at the bot- 

 tom 21 feet of red clay with irregular layers of coloured gyp- 

 sum. This gypseous red clay ranges to the north and south 

 of Ferrybridge, and in some places has been found 1 1 yards, 

 or even, it is said, 15 yards thick. It contains no trace what- 

 ever of organic remains. 



No. 4. —The limestone which is burnt at Knottingley and 

 Brotherton for agricultural uses, has at the utmost a thickness 

 of about 15 yards. In the quarries at Knottingley, 11 yards 

 is above the average. The rock is laminated through its whole 

 mass, but the lower layers are thicker. These are also in 

 general less hard and less compact, hold a few sparry con- 

 cretions, and some imperfect Axini and other bivalve shells. 

 By these characters they seem analogous to the lower or mag- 

 nesian rock ; and accordingly the lime burnt from them is ex- 

 cellent for building, but useless or even injurious to land. I 

 know not if the stone of these beds has been analysed. My friend 

 Mr. George, Secretary to the Leeds Philosophical Society, 

 found the upper part of the Knottingley and Brotherton lime- 



3 F 2 stone 



