10 
PHYSICAL GEOGRAPHY OF SUSSEX. 
marshy alluvial plain, through which the Ouse 
winds its way to the British Channel. This tract 
consists of silt, clay, and peat, and is nearly ten 
miles long ; its breadth varying from half a mile to 
two miles and a half. Towards the north-western 
confines of this plain are two remarkable oval 
mounds or hillocks of chalk marl, situated at a 
short distance from each other, near the borough 
of Southover. They bear the name of rhies ; a 
provincial term, derived from the Saxon hryg, a 
heap, or longitudinal projection *, and are about 
seventy feet high, and from two to three furlongs 
in length. 
* History of Lewes, 8vo. 1795, p. 416. 
