SUCCESSION- m THE TRENT BASIlf. 



449 



finely polished, striated, and grooved, especially the limestone or 

 hard coal and shale. The larger blocks vary from rounded to sub- 

 angular or angular masses. 



Another small patch of Boulder-clay caps the hill north-east of 

 Chaddesden and north-west of Brunswood. In a small ravine which 

 a brook has excavated in the west side of this mass of clay its 

 junction with the Keuper marl may be seen. The stiff blue clay 

 with boulders is contorted and crushed into the clay below, masses 

 of the one being sometimes torn off and buried in the other, while 

 boulders of finely polished and striated Carboniferous Limestone are 

 sometimes found in the disturbed clean red marl itself. A similar 

 section may be seen in the brook coming down from Borrowood. 

 Besting upon, or rather against, the Boulder-clay, and occupying a 

 depression or shelf in the side of the hill upon which Spondon is 

 built, there is a peculiar deposit of gravel of uncertain age. About 

 a quarter of a mile north of the " don " in Spondon on the Ordnance 

 Map, in a field by the stile-road, an excavation shows a section about 

 50 yards long and 14 feet deep. The stratification is indicated in 

 the upper portion by lines of fine pebbles or gritty sediment, and by 

 the general horizontality. The lower 2 feet contains beds of sand ; 

 one lenticular bed, about 8 yards long, consisted of alternations of 

 reddish and yellowish sand, while another was composed of coarser 

 sand, the false bedding of which indicated currents from the west- 

 north-west. These sand-beds contain carbonaceous matter. The 

 pebbles and boulders are of all sizes, generally well water-worn ; 

 but many are angular or subangular, particularly the larger boulders. 

 The pebbles are mostly quartzite, chert, gritstone, or Coal-measure 

 sandstone of finer grain. Other Pennine rocks are abundant. 

 The whole deposit is light brown in colour and contains a tolerable 

 percentage of argillaceous matter. Xear the surface the gravel 

 is slightly contorted by a force which seems to have come from 

 a north-north-west direction. In this disturbed portion there are 

 a few flints, a rock which is absent from the gravel below. The 

 junction of the gravel with the Boulder-clay is nowhere shown ; but 

 no similar deposit was met with, either in the Boulder-clay itself or 

 along the outcrop of the Keuper from beneath it. Of course it may 

 be urged that this gravel is the Quartzose Sand, and the Boulder-clay 

 the Early Pennine ; but it presents so many peculiarities that I 

 have not ventured to correlate it with that deposit. 



At Sheldon-Wharf brick-yard (fig. 1), south^ of Derby, on the 

 north-west side of the hill, near the canal, is an exposure almost 

 entirely excavated in Boulder-clay. The pit has been worked at 

 two levels : the lower one showed a section of 9 or 10 feet of a loose 

 broken red clay, with dicey pieces of Keuper marl and pockets of 

 sand. The whole mass at a distance very much resembles ordinary 

 undisturbed Keuper. Near the bottom it contains small bits of 

 decomposed gypsum ; while bits and patches of variously tinted clay 

 and pockets of light red clayey sand, with occasional small pebbles, 

 are distributed throughout the mass. Quartz and quartzite pebbles 

 and fragments of Carboniferous rock begin to make their appear- 



