part IJ GAULT AND LOWER GREENSAJSTD NEAR LETGHTOX. 3 



Buzzard. The bed differed, both in its lithological characters and 

 in its fossil contents, from any other deposit then known at this 

 horizon in England, and the problems which it presented demanded, 

 and have received, further investigation. Walker continued 

 assiduously to explore the palaeontology of the bed, until his work 

 was cut short suddenly by death in 1907. Partly by personal visits 

 to the locality, but mainly through the agency of the quarrymen, 

 lie had been able by this time very largely to increase his collection 

 of the fossils, and had made progress in his study of the brachiopod- 

 fauna, which was his particular interest. It was his intention 

 ultimately to deal exhaustively with this element of the fauna, and, 

 as a preliminary step, he had already prepared and sorted many 

 thousands of specimens into their proper specific relationship, with 

 provisional determinations where possible.^ The collections thus 

 arranged by his own hand are, however, all that remains to us of 

 the work that he did after the publication of our joint paper.^ 

 Some information culled from them will be given in a later part of 

 tbe present paper. 



While my late, colleague continued to explore the palaeontology 

 of the Shenley bed, I devoted attention, as before, more ^particularly 

 to its stratigraphical aspect. Visits in successive years constantly 

 revealed new features of interest during the continued excavation 

 of the Shenley sand-pits, and showed also that other pits in the dis- 

 trict Avere approaching the junction of the Gault with the Lower 

 Oreensand. Eventually I succeeded in obtaining evidence, long- 

 expected, for the presence of the JKammillatus Bed in sections 

 south of Leighton,*^ and afterwards in cuttings within half a mile 

 of Shenley Hill. 



The Leighton Sand trade received a great impetus as the 

 result of the War, wherefrom the old pits have been energetically 

 Avorked and several new ones opened. During last summer and 

 autumn (1920) I was able to undertake a leisurely examination of 

 all the sections, and I propose in this paper to combine the infor- 

 mation thus obtained with the observations gathered at intervals 

 since 1903, into a general review of the character of the Gault-and- 

 Lower-Greensand junction in the district. This junction is of 

 peculiar interest, and nowhere else in England has it been so 

 ■extensively displayed in open sections. 



^ See reference to this work in ' Obituary : John Francis "Walker ' Geol. 

 Mag. 1907, p. 383. 



^ By the liberality of his widow and his son, Walker's collection of 

 brachiopoda in its entirety was presented to the British Museum (Natural 

 History) at South Kensington, and the fossils other than brachiopoda were 

 similarly presented to the Sedgwick Museum at Cambridge. My thanks are 

 due to the authorities of these museums for the facilities afforded to me in 

 •examining the collections. 



^ Brief references to new features in the Shenley sections and to the dis- 

 covery of the Mammillatus Bed south of Leighton are contained in my reports 

 on two excursions of the Geologists' Association, 1908 & 1915, Proc. Geol. 

 Assoc, vol. XX, p. 475 & vol. xxvi, p. 310. See also my letter on ' Gault & 

 Lower Greensand near Leighton Buzzard ' in Geol. Mag. 1920. pp. 234 37. 



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