Which sentences in this excerpt from Ernest Shackleton's South! suggest that the author is writing a memoir?

AI looked down a sheer precipice to a chaos of crumpled ice 1500 ft. below. There was no way down for us.

BThe country to the east was a great snow upland, sloping upwards for a distance of seven or eight miles to a height of over 4000 ft.

COur path lay between the glaciers and the outfalls, but first we had to descend from the ridge on which we stood.

DThis tremendous gully, cut in the snow and ice by the fierce winds blowing round the mountain, was semicircular in form, and it ended in a gentle incline.

EWe passed through it, under the towering precipice of ice, and at the far end we had another meal and a short rest.