Studying Xenoliths at The Slab

Undergraduate students Tyler McLemore and Tyler West ("the Tylers") joined me for a weekend at the popular Hill Country field trip stop referred to as "Xenolith City" - known locally as "the Slab". Dozens of xenoliths of metamorphic rock in the 1.1 Ga Town Mountain Granite are exposed here in the Llano uplift. Students' many questions about the nature of the xenoliths, their origin, size, shape, orientation, and irregular margins led to this study. The Tylers measured xenolith length and width, and used a Brunton compass to determine the orientation of the xenolith's long axis and its foliation (if any). Tyler McLemore will analyze this data as part of an independent study this semester.