The west side of the divide offers the better access at present from several points off Ashlu Main. The eastern side of the divide is largely inaccessible, except at the extreme NE edge, where branch roads off Elaho Main provide access up Carol and Limelite Creeks. East side approaches are generally lower and steeper, due to the extensive Pleistocene glaciation down the Elaho and Squamish River valleys.
The bedrock is predominantly quartz diorite of the intrusive Cloudburst Pluton of the Coast Plutonic Complex, dating from the Jurassic or Cretaceous period. East and northeast of Icecap and Amicus Mountains, the margins of the divide are composed of a couple of lenses of older metamorphic rocks, predominantly comprised of granitoid gneiss, quartz diorite and schist.
Most peaks are relatively easy ascents from the icecap and many of them can be skied to the summit. The notable exception is Ashlu Mountain, which is the dominant peak of the divide and is prominent from many distant vantage points in surrounding areas. It has a distinctive pyramidal shape and steep, rocky ridges and faces well suited to rock climbing. History: The Squamish-Elaho corridor was first used by First Nations for fishing and hunting. Chilcotin Indians crossed from Lillooet River to raid an Elaho fish camp in the late 1800s. There was only one survivor of the raid- a child named Jimmy Jim, who later became chief of the Squamish band. Mount Jimmy Jimmy is named after him.
Mineral exploration and mining entered the Ashlu Valley and became prominent around the 1920s and 1930s. There was also some trapping by early white settlers such as Sigurd Andersen in the Elaho and Hank Tatlow in Sigurd Creek and possibly the Tantalus Range. A stash of rusting leghold traps was found by a BCMC party enroute to Zenith Lake in 1989.
It's speculative which of the peaks were first climbed by natives, prospectors or hunters. The ascent of Mount Wood was the first to be recorded in 1919. When logging roads entered the Ashlu Valley, Denton carried off most of the remaining first ascents in the early 1960s with Widdowson and Pringle, presumably for the VOC. After that, Icecap was climbed by a foursome in 1964 and Clarke snatched a pair around 1968. Fairley (1985) doesn't provide any information about who carried off Buck and Zig-Zag. Possibly these also received early first ascents that weren't recorded.