McMurdo sits on the southern edge of
Ob Hill seen from the road to Scott Base: the brick red colour on the lower slope is due to the oxidized scoria.
Oxidized Scoria at Ob Hill.
Pyroclastic deposits on the western slope of Ob Hill.
Across from Ob Hill along the road to Scott Base is another outcrop of the pyroclastic flow.
Halfway up Ob Hill, the rock formed from lava flow is being carved by strong winds.
The bed rock at McMurdo is laden with xenoliths. A xenolith is any rock caught/trapped within an igneous rock; i.e. the xenolith is a preexisting rock that was caught in the magma forming the igneous rock. Rocks from deep within the crust and even from the base of the crust can be brought to the surface as xenoliths. The xenoliths at McMurdo are bright green in colour and mostly made up of the mineral olivine. They could have been brought up from the mantle just below the crust. Some of the xenoliths are as big as a small apple and they look beautiful, studded in the dark, fine-grained rock.
A little to the Northwest of Ob Hill is Crater Hill another volcanic remnant and about 3 miles North of McMurdo is Castle Rock which is a volcanic neck composed of hard rock resistant to the erosive force of the wind. Numerous other small volcanic features have been mapped along the length of
Wishing you a Happy New Year!