Contributions to the geology of Mt. Ruapehu, New Zealand

Abstract

During the passage of the lahar, shortly after 10 o'clock on Christmas Eve 1953, a portion of the Whangaehu River rail bridge at Tangiwai was demolished by a raging torrent of mud and boulders which originated from the Crater Lake of Mt. Ruapehu, nearly twenty miles distant. This mudflow, or lahar, damaged the railway bridge piers and the Wellington-Auckland express plunged into the torrent. As a result, one hundred and fifty-one people lost their lives. During tramping and ski-ing trips over the past five years the writer has become well acquainted with the National Park area. Close inspection of the Crater Lake was made on 1 January 1954, and again on 22 January. On the latter date the writer was accompanied by two chemists from the Chemistry Department, Victoria University College, and one from the Dominion Laboratory of the Department of Scientific and Industrial Research, who collected samples of the lake water. On 24 January, the Whangaehu River was followed from the Desert Road to where it emerges from a deep gorge on the lower slopes of Mt. Ruapehu. A number of braided channels were examined on the alluvial fan that extends east from the outlet gorge almost to the Desert Road. On the same day the scene of the disaster at Tangiwai was also inspected