What is "letterklip"

The Letterklip, Afrikaans for "Lettered rock", is a provincial heritage site in Namaqualand in the Northern Cape province of South Africa.This unique rock formation was fortified, using dry stone walling, and occupied from 1901 to 1902 by the British forces during the Anglo-Boer War. Various regimental badges and officers' names are engraved in the rockface.