Fig. 2: Plots of the entropy S and mean roughness Ra values of archaeological samples from Duinefontein 2.
From: When was silcrete heat treatment invented in South Africa?
a Plot of 60 experimental reference samples (30 not-heated+30 heated) from the South African Western Cape region and their linear best fit (data from Schmidt, 2019). The black line marks the threshold, left of which no unheated samples plot, i.e., all unheated reference samples plot to the upper right of the line. The line cuts the best fit at Ln(Ra): 2.12. b Plot of 72 archaeological test samples onto the same fitted function and threshold line. Note that none of Duinefontein 2 test samples show values that could not be explained by the variability of unheated Western Cape silcrete.
