Ascending the Ferrar Glacier, which they named after the party's geologist, they reached a height of before being held in camp for a week by blizzards. This prevented them from reaching the glacier summit until 13 November. They then marched on beyond Armitage's furthest point, discovered the Polar Plateau and became the first party to travel on it. After the return of geological and supporting parties, Scott, Evans and Lashly continued westward across the featureless plain for another eight days, covering a distance of about 150  miles to reach their most westerly point on 30 November. Having lost their navigational tables in a gale during the glacier ascent, they did not know exactly where they were, and had no landmarks to help them fix a position. The return journey to the Ferrar Glacier was undertaken in conditions which limited them to no more than a mile an hour, with supplies running low and dependent on Scott's rule of thumb navigation. On the descent of the glacier Scott and Evans survived a potentially fatal fall into a crevasse, before the discovery of a snow-free area or dry valley, a rare Antarctic phenomenon. Lashly described the dry valley as "a splendid place for growing spuds". The party reached "Discovery" on 24 December, after a round trip of seven hundred miles covered in 59 days. Their daily average of over 14 miles on this man-hauling journey was significantly better than that achieved with dogs on the previous season's southern journey, a fact which further strengthened Scott's prejudices against dogs. Polar historian David Crane calls the western journey "one of the great journeys of polar history".