17 s geological survey report on lake bonneville 42 41 40 39 38 114 113 112 111 map of lake bonneville ( a water body of the quaternary period ) by g.k.gilbert assisted bv gilbert thompson israel c russell h a wheeler and albert l webster drawn by gilbert ancb j.m * ancient water surface r 40 r i>v ; note he topographic base was compiled from the published maps of the survey of the fortieth parallel , and from the published and unpublished maps of the p 1'h i f survey of the rocky mountxiirv regions ^/- and oftjw u s engineer surveys west of ¦ ^ r the 100 meridian together with the field r£^j notes oftlie geological survey 114 111 scale or i mch 12.626 miles jidiunbien & co.liih 0o miles 20000 metres •