The Echo Caves in Limpopo, South Africa, are set in Precambrian dolomite rock, which was first laid down about 3800 million years ago, when Africa was still part of Gondwana. The caves are considered some of the oldest in the world. The Echo Caves are about 92 km north of the similar Sudwala Caves. The caves were used for shelter in recent centuries by the Pedi people; they slept in what is now called the Samson chamber (due to the limestone columns which appear to hold the low roof of the cave up).