The existence of the entire structure of Filey Bay and the Brigg is caused by the fact that the rock on the south side of the Brigg slid down, causing the overlying clay to lie either at or below the level of the sea, which eroded it to form Filey Bay. The hard rock on the northern side juts out to form the Brigg. The structure still erodes and large rock slips caused by constant rapid erosion of the clay cliffs of Carr Naze have been witnessed. The last one occurred in 1869 and took away several hundred metres of the Naze.