"Hardpan" Quotes from Famous Books
 ... 940 ft. from the shaft, where the main overlying body of trap appeared in the heading. The full face of the tunnel was wholly in trap at about Station 275 30, and continued in this through to the Western Portal, where the top of the trap was slightly below the roof of the tunnel, with hardpan above. The contact between the sandstone and the overlying trap was very clearly defined, the angle of dip being approximately 17 40' ...
— Transactions of the American Society of Civil Engineers, vol. LXVIII, Sept. 1910 - The Bergen Hill Tunnels. Paper No. 1154 • F. Lavis |
