This epoch of great deformation and warping marks the transition from the Tertiary to the Quaternary.
The low lands adjoining the tidal reaches of the Trent and Humber, and part of those around the Wash have been raised above the natural level and enriched by the process of warping, which consists in letting the tide run over the land, and retaining it there a sufficient time to permit the deposit of the sand and mud held in solution by the waters.
A good sandy loam is common in the Heath division; a sandy loam with chalk, or a flinty loam on chalk marl, abounds on portions of the Wolds; an argillaceous sand, merging into rich loam, lies on other portions of the Wolds; a black loam and a rich vegetable mould cover most of the Isle of Axholme on the north-west; a well-reclaimed marine marsh, a rich brown loam, and a stiff cold clay variously occupy the low tracts along the Humber, and between the north Wolds and the sea; a peat earth, a deep sandy loam, and a rich soapy blue clay occupy most of the east and south Fens; and an artificial soil, obtained by "warping," occupies considerable low strips of land along the tidal reaches of the rivers.
(Since late Tertiary times) erosion has had but little effect in altering the country from the state to which it was brought by the uplifting and warping of the old peneplain.
Wooden pulleys are preferably made of maple, the rim being formed of small sections morticed, pinned and glued together, with the grain set in such directions that any warping of the material will leave the cylindrical form practically unaltered.