504 HESSKS. ARNOLD-BEMROSE AND DEELEY ON [Aug. 1 896, 



preserved by the bed of nearly impervious clay which has covered 

 them from the time they were first laid down. Secondly, the yellow 

 upper clay with pebbles strongly resembles the ' trail ' covering the 

 terrace and Keuper at other points. However, it was only exposed 

 for a few feet when the deep excavation was made, consequently 

 its horizontal extension and variation, as it passes from Keuper to 

 gravel, was not traced by open sections. Thirdly, such deposits as 

 fill the trough are not being formed at the present time on the 

 upper terraces. They are in fact being rapidly denuded from them, 

 and are now only to be seen at points distant from the edge of the 

 escarpment. The ridge separating Sinfin Moor from the gravel- 

 terrace is also very low and narrow, and there is no stream running 

 over the terrace which could have excavated the trough and then 

 allowed it to be filled again. On the other hand, it might be urged 

 that the trough was formed by the river immediately after the 

 gravel was contorted, and that the river deserted the Allenton side 

 of the valley soon after. This view, however, is scarcely so well in 

 agreement with the facts. 



At about the same level as the Allenton gravel-terrace a tongue 

 of red gravel runs up the valley on the south side of Kedleston 

 Brook. It is a red, indurated, sandy gravel which shows few signs 

 of stratification, but here and there contains small lenticular masses 

 of sand. The stones are sometimes large, generally well rounded, 

 and lie at all angles in the red sandy matrix. They are mostly 

 quartzites, but Keuper sandstone and flints also occur. The gravel 

 is about 11 feet thick and rests upon Keuper. 



The upper few feet of the Kedleston Valley deposit, where it 

 meets the Keuper on the south-western boundary, shades off into 

 red or yellow clay with pebbles. An excavation near Stretton's 

 Brewery, close to the edge of the gravel, exposed clay with stones 

 and sand, varying in thickness from 10 to 11 feet. It rested 

 upon contorted and broken, not redeposited Keuper marl. At this 

 point the whole deposit is ' trail ' and ' underplight ' rather than river 

 or brook gravel, and indicates the action of disturbing forces which 

 do not now act in the valley. 



I have dealt at some length with the Allenton terrace (and its 

 Kedleston extension) because the remarks made concerning it will 

 apply, with little alteration, to several other extensive deposits of 

 gravel and sand. Although we have called it a high-level terrace 

 it is by no means the highest of its class, for such gravels are to be 

 seen at higher levels along the course of the Trent as well as the 

 Derwent. In some instances they reach a height of 70 or 80 feet 

 above the alluvial plain of the river. In all cases they show con- 

 torted upper surfaces or intruded rolls of marl (Quart. Journ. Geol. 

 Soc. vol. xlii. 1886, p. 467). They have already been described at 

 some length in this Journal. Suffice it to say, therefore, that they 

 are portions of alluvial river-plains which mark former levels at 

 which the river ran, and which have escaped subsequent denuding 



