I found a helpful guide to the Durability of Bearing Trees on the Nevada Surveyors Site Compiled and prepared by C. Albert White, Portland Service Center Revised by Daryl K. Moistner (2008)
TREE…
BEARING TREE SET IN 10" OAK TREE ON JUNE 10, 1876 BY M.G. WHEELER 30 LINKS S 23-15 E TO WEST 1/4 CORNER, SECTION 1, TOWNSHIP 5 SOUTH, RANGE 2 EAST, S.B.M..TREE IS NOW 2.5 FEET IN DIA.