Glass (4-11 mu m) samples from 15 volcanic ash deposits were examined
for their suitability for optical dating. The samples ranged in age fr
om 8 to 500 ka. Only very weak luminescence was observed using 514 nm
(green), 633 nm (red) and approximate to 880 nm (near infra-red) stimu
lation. An equivalent dose of 29 Gy was obtained for Mazama ash using
near infra-red stimulation. This result agrees well with that obtained
earlier using thermoluminescence and is correct for its age of 7.7 ka
.