86 ME. E. L.SHEELOCK ON THE EELATIONSHIP OF THE [Feb. I9II, 



the corresponding surface-ridge, which terminates abruptly. It is 

 remarkable that these ridges of dolomite are untouched by de- 

 nudation, and it seems probable that they were formed by 

 comparatively recent movements along the fault-planes below. 

 These anticlinal domes will be mentioned again when I deal with 

 the districts to the north. They are, however, best seen in the 

 area now described, the most important one extending from 

 Aldercar Wood near Newstead to Bui well, and forming the boundary 

 of the Permian Marl in the southern half of its course. 



(e) The Area between the Robin Hood's Hills 

 and Mansfield. 



North of the Robin Hood's Hills, the Midland Railway runs 

 along the low-lying Permian Marl to the outskirts of Mansfield, 

 and on the rising ground to the east there are several sandpits in 

 the lower part of the Bunter, which is increasingly argillaceous 

 towards the bottom. At Kirkby Hardwicke the Permian Marl 

 has been almost reached, and at East Kirkby a brickyard shows 

 16 feet of Permian Marl with a sandy band, resting upon a floor of 

 Magnesian Limestone, and covered by about 6 feet of sandrock 

 (Bunter). 



At Sutton Junction a small north-north-westerly fault has cut off 

 an outlier of Permian Marl in Sutton-in-Asbfield. The fault is 

 visible in the Great Northern Railway on the west ; while on the 

 east a sandpit, in the Pebble Beds and Lower Mottled Sandstone, 

 shows it. 



About a mile and a half beyond Sutton Junction the Permian 

 Marl is cut out by a trough- fault, both arms of which can be seen 

 in a clay-pit, 400 yards north-east of King's Mill. The Marl, 

 however, reappears a quarter of a mile to the east, and can be 

 followed thence into Mansfield. 



Between Mansfield and Skegby there is a large outlier of Permian 

 Marl and Lower Mottled Sandstone capped by Drift. Along the 

 southern margin of the outlier a succession of clay-pits display 

 valuable sections, showing the entire thickness of the Permian Marl 

 and its junction with the Bunter above and the Limestone below. 

 The Limestone forms the floors of the clay-pits, and its junction with 

 the Marl seems always to be a well-defined lithological boundary. 

 On the other hand, the Marl is succeeded above by marly sandrock 

 similar to bands occurring within the Marl itself. At first sight, 

 there seems to be a fairly definite boundary below the saudrock ; 

 but, on examination, it is seen that this is mainly due to the water 

 which percolates through the sandrock being thrown out by the 

 first bed of Marl which it meets — with the result that the Marl 

 is a little undercut, and the base of the sandrock is bleached to a 

 pale greenish tint. 



Here, again, the boundary between Permian and Bunter is purely 

 artificial, and has been taken, as before, at the base of the 

 lowest sandy band of any importance. The Marl, as thus 

 defined, is fairly constant in thickness (about 15 to 20 feet), but 



