130 



HARDWICKE'S SCIENCE-GOSSIP. 



-estimate, for two reasons, (i) The plateau-gravels, 

 which cap the adjacent hills, and which he assigns 

 (as equivalents in time of his Mundesley and Westleton 

 Beds) to the beginning of the Quaternary period, 

 may be merely terrestrial deposits of the Pliocene 

 Mercian river-system, and more nearly equivalent in 

 time to the plateau-gravels of Berks and West 

 Surrey, being certainly older than the present Chalk 

 escarpment ; (2) the extent to which the gorge has 

 since been cut down to its present level, appears, 



/rem still more recently-published observations to be 

 greater than he has estimated.* We may, perhaps, 



•deduct 100 feet at least from his estimated 220 



is maintained in a most remarkable manner through 

 the contortions of the strata. Examples may be seen 

 in the railway-cuttings at Wokingham and Sunning- 

 hill, on the South-Western Railway ; but the finest 

 by far have been lately brought to light in the 

 excavations in the brick-yard of Messrs. T. Lawrence 

 & Sons, close to the Nine-mile Ride in Old Windsor 

 Forest.* Some of the best of these are gone for 

 ever, as the pits have been extended ; but, fortu- 

 nately for science, photographs were secured by 

 members of the photographic section which has been 

 recently started by the Natural History Society of 

 Wellington College. One of them, it is hoped, 



Fig. 106. — Section of Glaciated Clays and Gravel at Easthampstead, Berks, in Old Windsor Forest (March, 1891). 



■feet, as the vertical measurement of the work of 



• erosion during the Glacial Period. 



Professor Carvill Lewis estimated that the waters 

 of the above-named extra-morainic lake stood some 



1250 feet above the present sea-level in the old Thames 

 Straits of the Glacial Period. Now it is a remark- 

 able fact that at very near this elevation — that is to 



■ say, at levels varying from 220 to 240 feet — the author 

 has, within the last year or two, made a considerable 

 number of observations of glacial action in East Berks. 

 The laminated clays are highly contorted, and great 

 masses of sand and gravel, weighing in some cases 



jnany tons apiece, have been driven bodily, in a solid 

 (frozen) state, f into the clays, the lamination of which 



* See reference below to Mr. Shrubsole's paper. 



+ See "Journal of the Geol. Soc," vol. xlvi., p. 561. 



will be reproduced for publication by the Geo- 

 logists' Association of London. Subjoined is a 

 later photograph of a section, now also obliterated, 

 and only exposed to open daylight for a few days 

 in March, 1891. (See Fig. 106.) It was taken 

 by one of the author's pupils, Mr. McClintock, of 

 Wellington College. Copies of the earlier photo- 

 graphs were exhibited at the lecture, and some of 

 them have found their way to the Woodwardian 

 Museum at Cambridge, and to the British Association. 

 A little reflection will show that these marks of 

 ancient glaciation, probably the work of pack-ice, as 

 it was drifted and stranded by high winds on the 

 margin of the old Thames Straits, may be taken as a 



* A suggestion of Dr. J. W. Spencer, the State Geologist 

 of Georgia, when on a visit to the author last year. 



