Lines of malacopoesis etched on an anthropogenic landscape of invaders

Calcium carbonates from an archaeological shell midden, located on the headland in center frame, alter the species profile of grasses. None of the broad stands of "natural" appearing "wild" grasses visible in this photograph are native species, all are introduced invaders impacted by grazing activities in the past. The boundary of the shell midden is sharply defined by the reddish colored patch of grasses which are composed primarily of "rip gut brome" (Bromis diandrus) a type of rye. The surrounding yellow-green grasses are composed largely of "oats" (Avena sativa). What may at first sight appear natural, is in fact a cumulatively multilayered accretion of compounding historical processes.

Detail showing the sharply defined borders of difference.
In the photograph below, oats (Avena sativa) are shown below and the rip gut brome (Bromis diandrus) is shown above.