WHEN ROCKS FLOW LIKE TAR

King Country Chronicle, Volume VI, Issue 454, 6 April 1912, Page 3

WHEN ROCKS FLOW LIKE TAR

Under the pressure of the overlying weight, rocks at a depth of a fev miles become viscous, and are readj to flow like tar on removal of th« pressure from any side. The flow nay be shown even under artificial pressures, and in the experiments ol Professor P. D. Adams, marble hatbeen deformed and moulded with interesting and curious results. A cylinder of rock 4/5-inch in diameter ind 1J inches long, was fitted closely into a heavy tube of steel, and pressure was applied through pistons Df hardened steel. A thinner central portion of the tube permitted lateral sxpansion, while a temperature up tc L.OOO deg. could be applied by heating the tube in a stove. With pressures usually between 120,000 and 140, 000 pounds per square inch, the rock was pressed out of shape—sometimes rapidly, sometimes slowly, the time ;aken by the change ranging from ten minutes to six days. Undei 296,700 pounds per square inch i column of marble 1£ inches long anc 1 of an inch, expanding into a bar-rel-shaped mass, IJ.inches in diameter a t the centre. The deformed mar ble developed a fine foliated structure with no trace of granulation Curious results were that water hat 10 apparent influence, and that specific gravity was not changed.