East of Amman in Transjordan lies the basalt area called the Harrat er Radjil (the centre is approximately 37 deg. 30 mins. east and 32 deg. 30 mins. north), and this area is archaeologically most interesting. (Fig. I). The country consists mostly of basalt broken up into blocks of various sizes, with mud-flats scattered in all the hollows. The mud-flats are fed by small watercourses which are generally deeply eroded, and although they are usually dry, water flows in them after heavy rain. Pools of water sometimes lie in the watercourses and on the mud-flats till the commencement of the summer months. Here and there rise small crater-hills, a few hundred feet high, of volcanic formation; and here and there the larger watercourses have eroded the country, leaving many small hills which, when seen from afar, are not unlike the crater-hills.