Its age ranges from approximately 4.4 to 0.478 million years BP, spanning the late Pliocene and early to middle Pleistocene epochs.

The sands are characteristically dark green from glauconite but weather bright orange, with haematite 'iron pans' forming.

The highest formation in the Group, the Wroxham Crag, contains over 10% of far-travelled lithologies, notably quartzite and vein quartz from the Midlands, igneous rocks from Wales, and chert from the Upper Greensand of southeastern England.

[5] The sedimentary record is incomplete, leading to difficulties in correlating and dating sequences[6] The term Crag was first used in a geological sense by R.C.

Taylor in 1823, a word commonly used in Suffolk to designate any shelly sand or gravel.