It is typically difficult to gather without a hatchet or other cutting tool. Timber ranges from small logs two or three inches (76 mm) across to larger logs that can burn for hours.
There are three types of material involved in building a fire without manufactured fuels or modern conveniences such as lighters.
Another way is to cover the ground with sand, or other soil mostly free of flammable organic material, to a depth of a few inches.
Alternatively, turf may be cut away to form a bare area and carefully replaced after the fire has cooled to minimize damage. Bare rock or unvegetated ground is ideal for a fire site. If a fire ring is not available, a temporary fire site may be constructed. Ideally, campfires should be made in a fire ring. The data suggests humans were cooking prey by campfire as far back as the first appearance of Homo erectus 1.9 million years ago. Such fuel would not produce hotter flames. This is consistent with preliminary findings that the fires burned grasses, brush, and leaves. Microscopic analysis of plant ash and charred bone fragments suggests that materials in the cave were not heated above about 1,300 ☏ (704 ☌). Nearby evidence within Wonderwerk Cave, at the edge of the Kalahari Desert, has been called the oldest known controlled fire. A new analysis of burned antelope bones from caves in Swartkrans, South Africa, confirms that Australopithecus robustus and/or Homo erectus built campfires roughly 1.6 million years ago.