Much of east and northeast London lies on the modern floodplain of the Thames (spared from flood by the Thames barrier) or older terraces, a notable interruption being the remains of the artificial Beckton Alps. Pole Hill at Chingford and Lippitts Hill near Gilwell Park are capped by small outliers of Claygate Beds, while the higher parts of Epping Forest such as High Beach are Claygate and Bagshot beds with later gravels.