Western Cwm
The topography to the west is very complex so on 5 July Mallory and Bullock climbed the Ri Ring to get a better perspective. They were able to examine the upper North Face and the north ridge above the North Col and considered the latter was manageable. However, they formed a wrong impression that a high ridge ran from Everest's North Peak stretching away east to the Arun river. They therefore thought that any approach to the eastern side of the North Col could not be from Rongbuk, never imagining that the glacier on the other side of the North Col would turn back into the main Rongbuk glacier. In fact, where it joins, just above the Rongbuk Monastery, only a small stream is to be seen. Looking more to the west, two routes to Everest looked promising, one over the Lho La at the head of the Rongbuk glacier and one over an unnamed col between Pumori and Lingtren – the hope was that a valley to the south of these cols might provide a good route to the summit. Mallory climbed a peak he called the "Island Peak" (Lingtrennup) from where he attempted to photograph Changtse, Everest and Lhotse, which was just visible. They eventually reached the unnamed col by going west up what is now known as the Pumori Glacier and so by 19 July were able to look down into the Western Cwm and the Khumbu Glacier. They were not able to see the South Col but they thought the Khumbu glacier looked "terribly steep and broken" and anyway the drop from their col to the glacier was a "hopeless precipice". Any approach through the Western Cwm would therefore have to be from Nepal and by a different expedition.