Page:Quarterly Journal of the Geological Society of London, vol. 31.djvu/86

40 40 J. PKESTWICH ON THE QUATERNARY PHENOMENA Southwell this is overlain by another bed, due rather to rain- wash (see fig. 7, p. 39). At Lulworth and Arish Bay, a local angular drift-deposit of the some age flanks either side of the valley facing the sea. Other Drift Beds. The wide undulating tract of the Kimmeridge and Oxford Clays, Coral Rag, and Forest Marble between Portland and the Chalk range is generally perfectly bare. It is only at the following places that I have met with other small beds of drift : — 1. At levels of from 30 to 50 feet on the skirts of the hill between Portland Perry and Wyke. It is a coarse gravel, composed of sub- angular Chalk-flints and Greensand chert* with a few pebbles of Port- land flint, from 2 to 4 feet thick, and reposing upon a worn and eroded surface of Kimmeridge Clay and Coral "Rag (&", see Map and Sect. PI. I.). 2. Between Melcombe Regis and Furzeland are two low flat hills about 50 and 60 feet high, capped by a peculiar drift-gravel, which is worked on the left of the road turning off to East Chickerel. It consists almost entirely of subangular fragments of chert from the Upper Greensand, imbedded in a red clayey matrix, from 2 to 8 feet thick, sometimes covered with 2 feet of grey clay, and reposing in patches upon a very irregular bed of Oxford Clay. It was only after some search that I found in it a few small subangular chalk flints and a small pebble of white quartz. A similar gravel caps the hill half a mile west of the bridge over the Back-water (c, PL I.). 3. Traces of a coarse gravel-drift, chiefly of chert, exist on the top of Crook Hill, near West Chickerel ; but there is no bed of it. 4. On a hill between Weymouth and Broadway, east of Badipole, and at a height of about 70 feet, is a thin bed of gravel, composed of subangular chalk- and Portland flints, Greensand chert, large Sarsen-stones, and Tertiary flint-pebbles (c). 5. A similar gravel caps one of the hills midway between West Chickerel and Portisham. 6. A remnant of a much thicker deposit of gravel exists on the cliff immediately east of Osmington Mill, and again east of Eadcliff Point, at the higher level of about 150 feet. It consists almost entirely of a mass of brown subangular chalk-flints, many of them of large size, with a few fragments of Greensand chert, sandstone, and Portland flint, in red clay and sand, 8 feet thick (6'). 7. On a still higher level of about 300 feet, and capping the hill on the right hand of the road between Preston and Osmington, a small patch of fine flint and loess drift lies in hollows on the Portland Stone (6). 8. Another thick bed of still older gravel, composed chiefly of local Tertiary materials, overlies, and is scarcely separable from, the Tertiary beds at places on the highest points of the Chalk range f. t As I am uncertain of the extent of this bed, I have marked it on the map in one shade with the Tertiary beds, which also consist chiefly of sands and shingle-beds.
 * On one fragment was a cast of Pccten quadricostatus.