The tepuis are somewhat like that — made of genuinely ancient material, but shaped into their current form by processes that have been operating continuously through geological time.

The shape we see today reflects the current stage of a long erosional process, not a preserved ancient state.

Why The Cliffs Are Vertical

The cliffs of Roraima are not merely steep.

They are vertical, or in some places slightly overhanging, for hundreds of meters.

The question of why this is — why the mountain has walls rather than slopes — is answered by the geology of the rock layers themselves.

The sandstone of the Roraima Supergroup is not uniform throughout.