ASTRON C12 Lecture Notes - Lecture 12: Geology Of The Moon, Crater Counting, Radiometric Dating
Document Summary
Moon"s surface is composed of light highlands and dark maria Interior composition similar to that of earth"s mantle. The highlands are made up of rocks consisting of mostly one mineral - plagioclase feldspar (most abundant mineral of earth"s crust - but of different composition) The rocks from the lunar highlands have been dated with the sm-nd method are old about 100 my younger than the older meteorites. Covered by many layers of ejecta from impacts. A few meters thick on the maria, and 100"s of meters thick in the highlands. The outermost layer is a fine powder called soil - formed by micrometeorite impacts, weathers only over millions of years. Look at shape of craters to determine age. Stratigraphy - new layers overlap and cut across an older layers. Lunar stratigraphy - relative dating of different structures. Young structures (craters, for instance) lie on top of or cut across older ones.
