Enormous fractured boulders of gneiss were frequent over the whole of Mon Lepcha, from 7000 to 11,000 feet: they were of the same material as the rock _in situ,_ and as unaccountable in their origin as the loose blocks on Dorjiling and Sinchul spurs at similar elevations, often cresting narrow ridges. I measured one angular detached block, forty feet high, resting on a steep narrow shoulder of the spur, in a position to which it was impossible it could have rolled; and it is equally difficult to suppose that glacial ice deposited it 4000 feet above the bottom of the gorge, except we conclude the valley to have been filled with ice to that depth. A glance at the map will show that Mon Lepcha is remarkably situated, opposite the face of Kinchinjunga, and at the great bend of the Ratong. Had that valley ever been filled with water during a glacial period, Mon Lepcha would have formed a promontory, and many floating bergs from Kinchin would have been stranded on its flank: but I nowhere observed these rocks to be of so fine a granite as I believe the upper rocks of Kinchin to be, and I consequently cannot advance even that far-fetched solution with much plausibility. As I ascended, the rocks became more granitic, with large crystals of mica. The summit was another broad bare flat, elevated 13,080 feet, and fringed by a copse of rose, berberry, and very alpine rhododendrons: the Himalayan heather (_Adromeda fastigiata_) grew abundantly here, affording us good fuel. The toilsome ascent through the soft snow and brushwood delayed the coolies, who scarcely accomplished five miles in the day. Some of them having come up by dark, I prepared to camp on the mountain-top, strewing thick masses of _Andromeda_ and moss (which latter hung in great tufts from the bushes) on the snow; my blankets bad not arrived, but there was no prospect of a snow-storm. The sun was powerful when I reached the summit, and I was so warm that I walked about barefoot on the frozen snow without inconvenience, preferring it to continuing in wet stockings: the temperature at the time was 29·5°, with a brisk south-east moist wind, and the dew point 22·8°. The night was magnificent, brilliant starlight, with a pale mist over the mountains: the thermometer fell to 15·5° at 7.30 p.m., and one laid upon wood with its bulb freely exposed, sank to 7·5°: the snow sparkled with broad flakes of hoar-frost in the full moon, which was so bright, that I recorded my observations by its light. Owing to the extreme cold of radiation, I passed a very uncomfortable night. The minimum thermometer fell to 1° in shade.[109] The sky was clear; and every rock, leaf, twig, blade of grass, and the snow itself, were covered with broad rhomboidal plates of hoar-frost, nearly one-third of an inch across: while the metal scale of the thermometer instantaneously blistered my tongue. As the sun rose, the light reflected from these myriads of facets had a splendid effect.