KIMMERIDGE SHALE. 173 



coast-line, the cliffs averaging a height of about 190 feet. Thej' 

 consist of bituminous clays and dirt-beds, intercalated by 20 

 tabular layers of argillaceous limestones. At St. Alban's Head, 

 which is its most westei-ly extension, the series is more than 

 600 feet thick. It appears on the opposite side of the Channel 

 at Boulogne, testifying to the continuity of England with France. 

 It is probable the Shales derive their bitumen from the Saurians, 

 and the myriads of molluscs whose remains are compressed in 

 the laminated, paper-shales, and other fossiliferous beds of the 

 series. Between St. Alban's Head and Chapman's Pool the beds 

 are much disturbed and partly covered over ; on its western side 

 20 beds rise from the shore in succession. Soon after the two 

 first show themselves a fault throws them down out of sight. 

 They soon appear again followed by ton others in succession, each 

 separated by a clay-bed. The Kimmeridge Coal consists of two 

 beds, one locally called Blackstqne (2 feet thick), the other 

 Bubbicum (fifteen inches thick), succeeded by ^''os. 13 and 

 14, Avhich rise from the shore wlien Xos. 1, 2, 3, and. 4 have 

 reached the top of the cliff. Those re-appear on the west of the 

 anticlinal and dip into the sea near Gadcliff. Xos. 1.^, IG, 17 rise 

 from the shore within a distance of 250 yards. No. 16 is inter- 

 calated by a thin band of indurated schiste aliout 1 inch thick, 

 giving it the appearance of a double band. There are several down- 

 ward faults which in some cases send the beds below the sea-level, 

 but only to re-appear and commence again their slow ascent ; in 

 other cases a bed is brought down to the level of a lower one, 

 giving the appearance that both belong to the same. At Tower 

 Hill, on the eastern flaidc of Kimmeridge Bay, the bods are thrown 

 down some hundred feet. Nos. 16 and 17 are the first to appear 

 on the western side of Kimmeridge Bay, and run parallel to the 

 shore-line a considerable distance. Xo. 17, which through three 

 downward faults forms the three dangerous ledges of Charnell, 

 Broad-Bench, and Long-Ebb, is locally called Flat Ledge. 



It is probable the Shales were laid down in deep water beyon<l 

 the limits of an estuary of a large river, which carried down the 



