Page:Quarterly Journal of the Geological Society of London, vol. 28.djvu/549

1872.] the steep slope which marks the boundary of the valley near Wandsworth and Battersea Rise. It is seen along the valleys of all the tributary streams, which correspond in this respect with those on the north side of the river. This general description of the valley-gravels will, I trust, enable the reader to appreciate the position of the implement-bearing gravels under consideration.

My examination of the gravels in this district commenced in the year 1869, and has continued almost uninterruptedly ever since. A notice of the discovery of drift implements was communicated to the Meeting of the British Association at Exeter in that year. Several brick-pits were examined in the mid-terrace between Wormwood Scrubs, Shepherd's Bush, and Hammersmith; and the workmen had the appearance of flint flakes and implements explained to them by showing them specimens from other localities; rewards were also offered, to induce them to preserve any similar implements they might find during the excavations; but nothing of the sort was found in any of these pits. The brick-earth here lies from 10 to 12 feet thick upon the gravel; and, with a few exceptions, the cuttings did not extend lower than the brick-earth.

Passing westward along the Uxbridge road, I found that some excavations were being made for the foundations of houses in the high-terrace gravel in Churchfield, east of the village of Acton. The lay of the ground in this place corresponded so closely with that of the implement-bearing gravels of the Somme and the Ouse, that I determined to watch the diggings closely, and repeated my visits to this spot almost every day for some months. Reference to the section across the Thames valley from Acton to Richmond Park (fig. 5, p. 459), will show the position of this patch of gravel, resting upon the London Clay, a strip of which, as already mentioned, comes to the surface on the slope of the hill, dividing the high- from the mid-terrace gravel. Near this strip of clay the superincumbent gravel does not exceed 6 and 7 feet, and it is much contorted. Seams of sand may be seen to turn up nearly on end, a good example of which was seen in Section A, in Arthur Terrace, on the line of the 60-feet level. Higher up it increases to 10 and 13 feet thick, as was shown in Section G, in Lorne Terrace, between the 80- and 90-feet lines; and to the westward, in Home Lane, it was found in cutting for a sewer to be 18 feet thick. As a rule, the sections at the higher levels show the lay of the various seams of gravel and sand to be more even than in those parts which adjoin the outcrop of the clay, the seams thinning out gradually and horizontally in various directions. Between the 80- and 90-feet lines it was also noticed that in some places the gravel was overlain by a deposit of brick-earth, which passed down gradually and imperceptibly into fine sand. This was the case in Section F, in Chaucer