ROCKS OF THE ESSEX DRIFT. 



361 



being of considerable size. In connexion with the sandstones, 

 it may perhaps be worth mentioning that an implement made from 

 very hard sandstone was found on the surface close by Felstead, and 

 brought to me by the gentleman who found it. It is, I believe, 

 a Palaeolithic implement, of a shape rarely found in England, 

 and may have been lying in the clay ; this seems the more likely 

 from my having found two small implements and two abraded 

 quartzite pebbles in the clay-pit mentioned above. They were 

 taken out of a yellowish-white clay full of striated flints and resting 

 on chalky Boulder-clay. 



Limestones. — These are also found in considerable abundance in 

 the drift.; the specimens nos. 141-169 belong to the Carboniferous, 

 Triassic, Jurassic, and Cretaceous series. Of the Carboniferous, 

 there are boulders and fragments of all sizes, some being of con- 

 siderable size, for one measures 2 ft. 3 in. x 2 ft. x 1 ft. 3 in., and 

 another 2 ft. x 1 ft. 6 in. x 1 ft. They have become weathered to a 

 light bluish grey and are smoothed and rounded, but I have not de- 

 tected any striation. They are of a highly crystalline character, dark 

 grey in colour, hard, and fine-grained. The sections under the 

 microscope show some very perfect examples of Yalvulina, Endo- 

 thyra, Trochammina, &c, chiefly V. bulloides, V. Youngi, E. 

 Bowmani, and T. incerta, and in some of the sections the rkorn- 

 bohedral plates of calcite are very perfect. In addition to these, 

 there is one small piece containing Lithostrotion (no. 160). Of the 

 Triassic limestone there are two pieces from the Rhaetic beds, 

 nos. 162, 163, containing very good specimens of Pleuromya 

 crowcombeia ; one of these was taken from a railway-cutting at 

 Castle Hedingham, considerably beyond my radius, the other I 

 found near Felstead ; I am indebted to ilr. H. Keeping for 

 identifying them. They are somewhat interesting, because though 

 I see that the Ehaetic beds are said " to extend as a continuous, 

 though very thin band at the top of the Trias, from the coast of 

 Yorkshire across England to Lyme Regis on the Dorsetshire 

 shore " ('.Textbook of Geology/ A. Geikie, p. 766), yet I understand 

 that no Rhaetic beds come to the surface anywhere in the north of 

 England, and in that case these must be remnants of a very early 

 denudation. Of the Jurassic series, there is a great abundance of 

 blocks of all sizes, but I have taken only a few specimens, of which 

 one or two are from the Cornbrash, and the majority from the 

 Oxford Clay and the Kimmeridge Clay, containing Cardium, Tri- 

 gonia davellata, Ammonites serratus, &c. There are also two or 

 three pieces of Purbeck Harble, containing Paludina fluviorum ; but 

 inasmuch as-- this rock was much used for church-building and 

 building of priories &c, I feel that all of it that is not actually 

 taken out of the Boulder- clay must be looked upon with suspicion, 

 and this will necessarity apply to many of the Jurassic fragments 

 besides the Purbeck. Of the Cretaceous series, I have found one or 

 two blocks of glauconitic limestone of some size, one in particular, 

 measuring 3 ft. x 2 ft. 6 in. x 2 ft., which lies in an inn-yard iu Fel- 

 stead, and is very much weathered and worn : the section is numbered 



