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- a fine grained sedimentary substance. Clays can vary enormously in composition and colour and texture, but all are characterised by being able to retain water, and many become very plastic when mixed or beaten. Clay mortars and renders are far more widely used than has to date, been realised, many are mistaken for lime. Clay deposits are rarely more than 1m below the surface and can be 50m deep. A hole close to a building, which by now may serve as a pond, is probably the clay pit which provided the raw material for construction.

Clay lump is building in clay blocks, the clay is mixed with vegetable and/or animal fibre and rammed into moulds which are simple side frames. The blocks are air-dried and laid on mortar, usually of the same material. Puddled clay is obtained by mixing pure clay with one-fifth of its weight in water, to form a plastic material which can be used in construction to prevent the passage of water eg lining ponds. Clay thatch where clay is used as a top dressing, for fire protection, or to secure the heads of bundles of straw/reeds etc was a practice more widespread than is generally realised.