Archaeologists define a chopper as a pebble tool with an irregular cutting edge formed through the removal of flakes from one side of a stone. Choppers are crude forms of stone tool and are found in industries as early as the Lower Palaeolithic from around 2.5 million years ago. These earliest known specimens were found in the Olduvai Gorge in Tanzania by Louis Leakey in the 1930s. The name Oldowan was given to the tools after the site in which they were excavated. These types of tools were used an estimated time range of 2.5 to 1.2 million years ago. Formation To create this tool, one would have to use a hammerstone to chip away flakes on the stone to create a side of the stone with a very sharp edge, allowing for the cutting and hacking of an object. This is a unique type of lithic reduction, as only a single side of the stone is retouched to produce the cutting surface of the stone. The side that does not do the cutting is left unscathed, an unusual practice. These old instruments were made from specific materials. Initially, they were composed of quartz, quartzite, basalt, or obsidian. In the later years of the Oldowan age, two other materials were used: flint and chert. These materials could hold an edge while still being fairly easy to craft into the shape desired. The tool is designed to fit in the palm of the hand, and it is not attached to any other mount that could possibly be used. Known as one of the earliest tools (if not the earliest), its design is a very simple piece of technology, but its performance was very successful in many different scenarios. Seeing the history of these objects and how many cultures used them, it is not a surprise to find them spread throughout the world. A potential stone mass found today could be classified as a chopper if it has a worn edge showing evidence of tool use. Locations Choppers are not solely limited to a single area on Earth: As mentioned earlier, Africa is known to have supplied the earliest known choppers, specifically known as the Oldowan. Many countries have given sites containing many of these stone tools, including Egypt, Ethiopia, Kenya, Tanzania, and South Africa. In North America, similar stone tools have been found in south and southwestern states, such as Oklahoma.