Show 49 periods of the ancient lake it should not be concluded that they make up its whole history A study of the mountain sides surrounding the lake shows numerous terraces interThese however mingled with these three outstanding ones are less prominent and indicate that the lake remained at those levels a comparatively short length of time An intricate study of the lake of the various levels lies outside the scope of this work As soon as geologists had established the fact that a great lake had once filled a large portion of the Great Basin they began a search to determine what had become of this vast inland sea As a result the shore line was examined for a place where the lake had overflowed It was found that the water of Lake Bonneville approached the summit in several places North of Snowville it came within 100 feet of the basin rim at a pass north of Kelton it came within 75 feet However the actual point of overflow was at Red Rock Pass immediately north of Cache valley in southern Idaho The outflowing river entered Marsh Creek valley joined the 17 Pass Portneuf and entered Snake river by way of Portneuf rd of a mile wide and Red Rock Pass is about one-thi- has been al small 17 partially filled with debris and deposits from severcreeks that flow into it Most of these streams Gilbert Lake Bonneville 172 173 |