Qal'eh Hasan Ali consists of maars,[4] and it covers a surface area of 150 square kilometres (58 sq mi).[6] 14 craters are found within the field, two of which are separate from the rest of the group. The craters have diametres of 150–1,000 metres (490–3,280 ft) and depths up to 80 metres (260 ft); the largest crater ("Great Crater" (29°23′39″N 57°33′29″E﻿ / ﻿29.39417°N 57.55806°E﻿ / 29.39417; 57.55806[7]) reaches a diametre of 1,200 metres (3,900 ft) and depth of 200–300 metres (660–980 ft);[8] it also contains a salt pan.[9] This crater has an altitude of about 2,300 metres (7,500 ft) above sea level.[2] These craters are surrounded by rims of fragmentary rocks,[1] which form beds with thicknesses of several 1 centimetre (0.39 in). These beds have steep outward and much more gentle inward dips and are mostly constructed from country rock; only on two craters including the Great Crater has juvenile material been found.[10] Some craters may have been affected by fumarolic activity, which has left sodium sulfate minerals such as mirabilite.[8]