In the Cleveland ironstone mines which are largely post-1850 the shafts were almost all circular in plan. A couple can still be seen (from 1855 and 1872) which are square but the most exceptional is at Esk Valley mine from the 1860's (NZ 822044) which is rectangular and accommodated two square cages, side by side, and a set of pumps. The shaft lining is well-made of ashlar sandstone and the two long sides are distinctly concave by a few inches presumably to resist side pressure. Total depth was 200 feet but only some 20 feet are now visible.
Simon.
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