Coralline Crag at Aldeburgh Brickyard

CORALLINE CRAG AT ALDEBURGH BRICKYARD AN interesting exposure of Coralline Crag was found on Ist October, 1966, when we visited the pit which had been largely hidden by a refuse dump.

This Crag was formed as reefs in the Coralline Crag Sea during the Pliocene epoch. These reefs were composed mainly of the remains of colonies of Polyzoa (Bryozoa) or Corallines and the shells of a variety of Mollusca. These shells were composed of two forms of Calcium Carbonate—Calcite and Aragonite, the latter were dissolved by percolating water and the Solution cemented part of the deposit into a soft type of limestone. This limestone was formerly quarried near Orford and used in the construction of Orford Castle by Henry II and for the tower of Chillesford Church (14th Century), and in Monastic buildings at Dunwich.

On the Coralline Crag is a thin bed of sandy Crag with Molluscan remains, including Scrobicularia plana, a species not found in other parts of the Crag series, possibly transitional between the Red and Norwich Crags.

Laminated Clay occurs above the Crag Sand and was formerly thought to be part of the Chillesford Beds, until Dr. R. G. West established by pollen analysis that it was deposited in a cold sea towards the close of the Norwich Crag series.

Only this Laminated Clay could be seen to advantage in the Brickyard—one of the few places in SufTolk where bricks are still made, though the clay was formerly worked at Frostenden and a small brick and tile works exists at South Cove, near Southwold.