Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/307

1870.] WILSON RUGBY SURFACE-DEPOSITS. 199 At Lutterworth the sand and coarse gravel is 40 feet thick.

At Harborough Magna the sand and gravel are 70 feet thick ; and about a mile from the village one well was sunk 90 feet, through gravel, clay with pebbles, and, finally, sand.

In the railway-cutting between Brownsover and Newbold, on the Rugby side of the canal, is sand mixed with loam containing flint, syenite, and various kinds of quartzite. Beyond the canal are striated stones of various kinds, chalk and syenite in similar sand, which is there seen to rest on rudely stratified clay with chalk pebbles, below which are other deposits of sand. Near the canal here is a patch of re-formed Lias clay, with abundant blocks of striated Lias limestone, but no chalk.

At Easenhall the gravel is deep and very wet.

At Newnham gravel is almost wanting.

General Summary of the Surface Deposits.

Deposits on the high Lands.

It appears, then, that on the Rugby plateau, and on the similar high lands in the neighbourhood, the Lias is generally, but not universally, capped with three kinds of superficial deposits. These are —

1. The flinty and quartzose drift.

2. Sugary sand with grains of chalk.

3. Clay with pebbles, principally of chalk, distinctly striated. Of these 2 and 3 are generally found together, and either may lie on the other ; 1 lies over both, and is never found below either ; 2 and 3 are never found in any thickness except where lying on the slopes of the hills, and they follow the steep slopes of the valleys with great pertinacity ; 1 is found principally on the high levels, thins out everywhere down the slopes, and never reaches the bottom of the valleys ; 3 is similarly entirely wanting in the valleys, as far as at present ascertained ; 2, or a modification of it, is found in one valley.

Deposits in the Valleys.

The valleys in this neighbourhood are of various widths, sometimes widening out into broad plains, at others very narrow with steep slopes. There are two systems of valleys divided by the Rugby plateau — the valley of the upper Avon on the north, and that of the Leam on the south. The bottom of the valley is generally a narrow strip of alluvial soil, bordered by sand in some places, by drift in others, while, again, in other places all the surface-deposits are wanting. No wells or other excavations exist in the valleys ; and I determined to make some borings with a view to ascertain the nature of the underlying strata. It might have been presumed that the valleys were excavated in the Lias clay, and that therefore just below a few feet of alluvial soil we should find the Lias. The result is startlingly different from what I expected. I have examined only the valley of Lowmorton in any detail. This is a lateral valley of the Avon,

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