Has anyone any experience using a proton magnetometer in an urban setting, particularly over roadbeds? We have recently used ground penetrating radar on several different sites. The results can be useful, but they are generally difficult to interpret without test trenching. We would like to supplement the ground-penetrating radar with other means of geophysical prospecting in zones where it is not feasible to do trenching, notably on high-traffic city streets. A proton magnetometer survey would seem to be one possibility. Please note that we have considered the question of doing core-samples, but we want to fully investigate the question of non-invasive testing first. We would appreciate any comments or references to the question. Thanks in advance for your help. William Moss Archeologue principal Design et patrimoine Hotel de Ville C.P. 700, Haute-Ville Quebec (Quebec) Canada G1R 4S9 Tel. : 418-691-6869 Fax : 418-691-7853 email: [log in to unmask]