Kopje

In one spot only was the solemn monotony of the plain broken. Near the center a small solitary “kopje” rose. Alone it lay there, a heap of round ironstones piled one upon the other, as over some giant’s grave.

Source: wiktionary

We selected a lichenous kopje perhaps fifteen yards away, and landed neatly on its summit one after the other.

Source: wiktionary

It was nearly noon when he reached the great bowlder at the top of which terminated the secret passage to the pits beneath the city. Like a cat he scaled the precipitous sides of the frowning granite kopje.

Source: wiktionary

Martha looked over a mile or so of bush to a strip of pink ploughed land; […] and then, ridge after ridge, fold after fold, the bush stretched to a line of blue kopjes.

Source: wiktionary