Reviews — Memoirs of the Geological Survey. 85 



IV. — Memoirs of the Geological Survey. 



1. — The Geology of Holderness, and the Adjoining Parts 

 of Yorkshire and Lincolnshire. By Clement Eeid, F.G.S. 

 8vo. pp. 177. (London, 1885.) Price 4s. 



THIS Memoir is devoted to an account of the Glacial and Post- 

 Glacial deposits of the Holderness district, that are included in 

 the area of Sheets 85, 86, and 94 of the Geological Survey Map. 

 The district was surveyed in part by Mr. J. K. Dakyns and in part 

 by Mr. A. C. G. Cameron, as well as by Mr. Eeid, who however has 

 a personal knowledge of the entire region. 



The Drift-deposits of Holderness occupy an old bay bounded by 

 Chalk hills, a bay whose form is due to the relative hardness of the 

 lower and upper beds of Chalk, the former standing out in the bold 

 headland of Flamborough. The Drift-deposits have been banked up 

 against the old line of Chalk cliffs, in places to a depth of 100 feet, 

 so that while geologically speaking the ancient Bay of Holderness 

 has been preserved, physically speaking it has been obliterated or 

 smothered up. 



The oldest Boulder-clay, known as the Basement-clay, is interest- 

 ing from the occurrence in it of transported masses of sand and clay 

 full of mollusca. These fossiliferous layers have been described 

 under the name of Bridlington Crag ; but the view that they are 

 included in the Glacial Drift, advocated by Mr. S. V. Wood, has (with 

 a different explanation) been confirmed by Mr. G. W. Lamplugh and 

 Mr. Eeid. It was indeed previously announced in the Geol. Mag. 

 (Vol. 1. 1864), by the late Dr. S. P. Woodward, that the Bridlington 

 deposit can no longer be considered the equivalent of the Norwich 

 Crag, being of an Arctic character, a conclusion which, as Mr. Eeid 

 remarks, " subsequent discoveries have only tended to confirm and 

 strengthen." A revised list of organic remains from the Bridlington 

 Crag is now published, and this includes, besides Mollusca, Plants, 

 Foraininifera, Cirripedia, Entomostraca, and Vertebrata. The Verte- 

 brata are probably derived from Crag, Eocene, or older deposits. 

 Eemains of Echinodermata and Polyzoa have been found, but these 

 as yet are undetermined. Mr. Eeid observes that while the Base- 

 ment-clay is the lowest bed exposed in the Holderness cliffs, the 

 Chalk is generally about 60 feet beneath the sea-level — hence older 

 Glacial or even newer Pliocene beds may be concealed in places. 



Above the Basement-clay, other layers of Boulder-clay, known as 

 the Lower and Upper Purple Clays and the Hessle Clay, are locally 

 to be distinguished. Mr. Eeid makes some important observations 

 on the weathering of Boulder-clay, whereby chalky Boulder-clay 

 passes into reddish-brown stony loam. 



Associated with the Boulder-clays are marine Inter-Glacial and 

 other gravels and laminated clays. The Inter-Glacial beds have 

 yielded mammalian bones, and a marine fauna indicating a climate 

 that seems to have been little if at all colder than that of the same 

 region at present. A full list is given of the organic remains found 

 at Kelsey Hill, and other places, and a column showing the forms 



