Great Glaciers In Those Days.

Star (Christchurch), Issue 19154, 21 August 1930, Page 8

Great Glaciers In Those Days.

Nature Notes .

By

James Drummond, F.L.S., F.Z.S.

JN ANCIENT TIMES great glaciers crept down from the snowfields as the Southern Alps were forced higher and higher. The mountains reached their greatest elevation probably at a time contemporaneous with the Great Glacial Age in Europe. With reduced supplies of snow the glaciers began to retreat. In addition to this, the whole land may have somewhat subsided, and the climate may have become warmer. In any case, in their retreat, the glaciers left behind them moraines in which geologist? read their history. The glaciers advanced and retreated again and again. For a long time they subdued and occupied a large part of the present lowlands. Advancing and retreating, they busily carried their loads of rocks and gravel, to drop them here and there. The final retreat into the frozen heart of the mountains is going on still. Near the alpine divide, south-west of the Whitcombe Pass, the Bracken Snowfield gives some idea of the extent of the snowfields that fed the old-time glaciers. The Bracken occupies a large area of almost flat or gently sloping country, 7000 feet high on the average, with here and there a rocky peak or a ridge more than 8000 feet high. The snowfield is at least from 100 feet to 200 feet thick. Creeping over the alpine divide, it links up with snowfields that feed the Ramsay Glacier, on the eastern side of the Southern Alps. This glacier, an extensive one, is the source of the main branch of the Rakaia River. In the same district as the Bracken Snowfield, there is a small snowfield, on a gentle siope that falls from the summit of Mount Bowen, 6500 feet. Crevasses show that this mass, in places, is 100 feet thick.