  When a large blunt object penetrates into a granular material, the force
response exhibits an initial nonlinear relationship with depth that is widely
attributed to the formation of a shear jammed stagnant zone. We present an
experimental study of a model 2D granular system that preserves common aspects
of slow granular penetration, such as a linear force law for large depths,
while also allowing for direct and precise measurement of a stagnant zone. We
also probe structural anisotropies throughout the bed and examine their
characteristics inside and outside the stagnant zone. Finally, we
simultaneously consider effects of concave elongated particle shapes (dimers)
and find that while most results are not affected, the relationship between
local structure and strain suggests a distinct fragility in the stagnant zone.
