 The Triassic deposits were formed in a Sahara -like desert when the British Isles lay about 15 degrees north of the equator, whereas the clays represent deep-water sediments.The landscape here is flattish, with the only feature of note a rather weak low scarp which meanders across the vale from SW to NE marking the Triassic/Jurassic border.This is superbly illustrated at the ‘Garden Cliff’, Westbury-on-Severn (see picture), where the river Severn has sliced a convenient ‘cut-away’ section of this transition from the red Triassic marls, through the thin Penarth Group (formerly 'Rhaetic') strata, to the lias clays and limestones of the lower Jurassic.