Yellow sandstone, Sussex

These Cretaceous sandstones in the image below, laid down around 110 million years ago, contain few fossils. Those fossils that have been found are of sea-shells.

Slanting beds (large-scale cross-bedding) like these are laid down in fast-flowing tidal currents today, so these sands may have been deposited by ancient tidal currents that swept the sand along as shown in the diagram.

These crumbly, soft sandstones are now quarried for building sand. The yellow colour is due to iron compounds cementing the grains together.