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Geologic materials Rocks (including high and low porosity & crystalline), unlithified or poorly lithified sediments, and soils

Primary versus Secondary Structures Form when the rock forms, thus provide a record of geologic processes May be present in sedimentary, volcanic, and intrusive rocks The former two cases generally have better way-up indicators Modify - sometimes obliterate - primary structures Commonly, though not always, oblique to primary structures May be continuous (pervasive) or discontinuous

Why we care about primary structures in a structural geology class Being able to distinguish primary from secondary structures is critical to reading rock record Geologic history (tectonics) Way-up indicators Material controls on deformation

Description What is the rock type? What do structures look like (e.g. shape, continuous or discontinuous, etc.)? Is it homogeneous or heterogeneous? Isotropic or anisotropic? Is it primary or secondary? How would you interpret this structure? Can it be used as a way-up indicator?