Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/73



The uppermost of the beds detailed in these sections consist of sandstone and shale, and they are the first that rise from beneath the coal formation. The most remarkable of the sandstones are

1. The slate sill, a fine grained, micaceous, slaty rock of a grey colour, used as a roofing slate in many villages of Northumberland and Durham. It is the uppermost bed in the section of Hely field.

2. The freestone sills: these are fine grained sandstones frequently containing vegetable impressions.

3. Hard ferruginous line grained sandstones called hazles by the miners. The sandstone in the section of Aldstone moor, called nattras gill hazle, is however coarse grained. These are sometimes slaty, and occasionally bear the impressions of bivalve shells.

4. The millstone grit, a coarse white sandstone composed of small angular grains of quartz, with rounded pebbles of the same