Original sentence: Ubehebe Crater is a large volcanic crater located at the north tip of the Cottonwood Mountains  that is half a mile (one kilometer) wide, 500 to 777 feet (150 to 237 m) deep, and 4-7 thousand years old (Native American artifacts in the area indicate that 6000 years is the most likely age although estimates of 2000 years are common)
Edited sentence: Ubehebe Crater is a large volcanic crater located at the north tip of the Cottonwood Mountains  that is half a mile (one kilometer) wide, 500 to 777 feet (150 to 237 m) deep, and four to seven thousand years old (Native American artifacts in the area indicate that 6,000 years is the most likely age although estimates of 2,000 years are common)