See Post 2,579 link below: I estimate the Amphibolite layer/section to be just under 2ft in length. What was more striking to me was that since coring was vertical, the Amphibolite section in the "middle", was sandwiched on each end with differing rock; - infers a laminar "seam". Not exactly a simplistic geological strata layering for structural engineering. Note the fractures in the core sample, including the Amphibolite section.