ON THE EBKATIC BLOCKS OF ENGLAND, WALES, AND IRELAND, 115 



specified -whicli are less tlian 12 inches in length, thoagh there are an 

 immense number which fall only a little short of that limit, especially 

 boulders of igneous rocks: but even with the omission of these the list 

 is not by any means an exhaustive one, as some portions of the district 

 have scarcely been examined. They have been found within six miles of 

 the village of Felstead, which will be found marked on the Ordnance 

 Map nearly mid-way between Braintree on the east, Dunraow on the 

 ■west, Little Saling on the north, and Great Waltham on the south. The 

 general character of the district is that of a tableland, ranging from 200 

 to 250 feet above sea-level, intersected by small valleys cut out chiefly by 

 local streams. The superficial deposits are chalky boulder clay and beds 

 of glacial gravel : these gravel beds really underlie the chalky boulder 

 clay, as could be well seen in the railway cutting | mile west of 

 Dunmow Station before it was overgrown, but owing to the extensive 

 denudation of the clay the beds of gravel are frequently found at the 

 surface on the high ground. London clay underlies all these superficial 

 deposits, and in several valleys, notably that of the Chelmer, the streams 

 have cut their way down to it ; nearly all the larger boulders have been 

 found on the high ground. Some of these seem to require special 

 mention. Of the sandstone boulders three measure respectively 

 77 X 36 X 20 in. and 6-i x 63 x 14 in. and 61 X 34 x 17 in., this last having 

 a circumference of 158 inches, and nine others exceed 40 inches in 

 length, including the conglomerates : nearly all appear to be unfos- 

 siliferous, but in one, which in texture and general appearance may 

 be considered characteristic of the greater number, I found some small 

 fragments of Crinoid stems and some casts of portions of Aviculopecten : 

 in another rounded boulder of about 12 in. in diameter I found some 

 very well defined casts of Productus (P. semireticulatus, P. Martini, 

 P. orthoceras, P. hemisphericus), Streptorbynchus crenistria, Euom- 

 phalus pentangulatus, Bellerophon, showing that the boulder was mill- 

 stone grit ; and Mr. H. Keeping, who also examined the casts, tells me 

 that it agrees very well with the beds of buff sandstone near Oswestry. 

 Li two other large boulders, which 1 have described in a previous paper 

 CQ. J. G. S.' August 1887, p. 360) as being masses of a greyish yellow- 

 sandstone permeated with a thin film of calcite, giving them a peculiar 

 glazed appearance wherever fractured, I found fragments of Pecten 

 orbicularis. Mr. Whitaker informed me that a great number of boulders 

 of this rock are found in the boulder clay in Norfolk, and Mr. Keeping 

 identified it as being of the same character as that which occurs in the 

 Spilsby beds in Lincolnshire. Another very large boulder of a buff 

 coloured sandstone, fine-grained but not very compact, was dug out of 

 the bottom of a pond a few weeks ago : it contains Belemnites in 

 abundance, some of a large size. Among numerous boulders of Hert- 

 fordshire pudding-stone there are two which measure respectively 

 52x23x16 in. and 52x43 in., this latter being so completely buried 

 in the ground that its thickness could not be ascertained. The lime- 

 stone boulders are fragments of Carboniferous, Jurassic, and Cretaceous 

 rocks. The Carboniferous are almost without exception so exceedingly 

 fine that scarcely any fossil shells can be detected in them without the 

 aid of the microscope, the one exception being a boulder lately dug up at 

 Bocking Place almost entirely composed of shells of Productus giganteus. 

 Of the Jurassic rocks two boulders of Kimmeridge clay, taken out of 

 the chalky boulder clay in the cutting near Dunmow, were wonderfully 



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