Lunar hadley rille: considerations of its origin

Science. 1971 May 14;172(3984):722-5. doi: 10.1126/science.172.3984.722.

Abstract

Geomorphology, topographic configuration, comparisons with terrestrial analogs, and considerations of the chemical and physical characteristics of mare lavas indicate that the Hadley Rille is a lava channel. Some of the structure was roofed to form a lava tube, parts of which have subsequently collapsed.