Disclosed are a tool and method for identifying the relative strength of subsurface intervals through which a borehole has been drilled. The tool includes a tool body capable of being moved through a borehole. The tool body has pads mounted on movable arms. Preferably the arms can be loaded independently. Each pad (42) carries scratchers (14, 16), which are pushed against the borehole wall so as to create either deep narrow or shallow wide scratches. Preferably, the scratchers comprise either a single or dual element polycrystalline compact (PDC) cutter or suitable hard, wear resistant material such as tungsten carbide or natural diamond, and are pushed against the borehole wall by resiliency loaded arms. The depth of narrow scratches is measured, for example, by two tandem powered calipers and the width of wide scratches is visualized by a borehole imager.
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