156 F. L. Kitchin c& J. Fr ingle — The Upper Gault in 



of hard lavas of St. Helena by the untiring waves. On the windward 

 side of that island, the 20-foot strand marks have apparently been 

 already destroyed. The more moderate, though absolutely powerful 

 surf on the leeward side has damaged the 20-foot benches, but has. 

 left many remnants. From these, when compared with the initial 

 shapes and volumes of the benches, it is clear that the sea -erosion 

 is exceedingly slow. The stupendous cliffs of St. Helena seem to 

 represent a duration of wave-attack which may be reasonably 

 guessed as more than 2,000,000 years. 



Barring a fault, visible in the north-eastern sea-cliffs of 

 St. Helena — a displacement of about 30 feet — a few insignificant 

 slips seen in tuff-beds, and the local deformations incidental to 

 igneous injection, the island seems free from the effects of diastrophic 

 processes. The field evidence points to the conclusion that St. Helena 

 has neither sunk nor risen for a very long period of time, if, indeed, 

 it has moved at all since the distant epoch of its last eruption. 

 Ascension, too, shows no indication of having either risen or sunk 

 since its beginning as an island. 



In 1923 the writer hopes to publish the geological maps and the 

 details of his studies on these instructive islands. The results are, 

 of course, but supplementary to Darwin's classic descriptions in his 

 Voyage of the Beagle and Geological Observations on Volcanic Islands. 

 Anyone honoured with the opportunity to follow the very paths he 

 trod in out-of-the-way places cannot merely admire his famous 

 accuracy and thoroughness of observation. Even more impressive 

 is the evidence of Darwin's intellectual initiative in the field of 

 geology. He created much of the technique of the science ; most 

 literally he was one of its founders. In the main Darwin's, 

 descriptions of these islands are amazingly full and true to the 

 objective facts, because he had the genius to discover the vital 

 problems and to invent the technique for handling them, as, alone 

 and single-handed, he attempted the mysteries of the volcanic 

 islands. A few changes in his theoretical conclusions are necessary, 

 chiefly because he lacked the methods of study which three 

 generations of geologists have since developed. The principal 

 changes refer to the relations between the basalts and trachytes of 

 Ascension (where he failed to discern the superposition of the 

 trachytic bodies on the older series of basalts) and to the nature, 

 location, and physiographic development of the volcanic vents and 

 magmatic types on St. Helena. 



On the Overlap of the Upper Gault in England and 

 on the "Red Chalk" of the Eastern Counties, 



By F. L. Kitchin, M.A., Ph.D., and J. Pringle, F.G.S. 



I. Intboduction. 



"PvURINGr the years 1918-19 we investigated the relations of the 



-^ beds exposed in a remarkable section at Shenley Hill, north of 



Leighton Buzzard. Our conclusion that lenticles of limestone of 



