HOW MOUNTAINS FORM.

Auckland Star, Volume XLVII, Issue 206, 29 August 1916, Page 7

HOW MOUNTAINS FORM.

ATJCIO-AND INSTITUTE LECTURE. BY MR. J. A. BAETRUM, M.Se. The origin and growth of mountains was explained by Mr. .1. A. Hartrum. Ml.Se., in the course of a lecture at St. Andrew's Hall last night, under the auspices of the Auckland Institute- Professor 11. W. Segar presided over a large attendance.

Limelight illustrations were provided by mcnns of a splendid set of slides, which were descriptive of geological and scenic features of mountains throughout the world. The lecturer said that the most important type of mountain was the volcanic, and be proceeded to describe how sometimes lava poured out of the actual vent in the volcano, and rushed j into the water, a-i hail boon the case at Point Chevalier. Tlie Auckland volcanoes, bow-ever, were mere babies as compared with those of South America. Furthermore, tbe Auckland volcanoes were believed to be of very recent date, as evidenced by the preservation of their round cones. Mr. Biirtrum went on to explain the ellcct of erosive agencies and in doing so screened some remarkably tine pictures of mountains in New Zealand and in foreign parts. In describing the formation of mountain masses by volcanic action, the lecturer said that in the first instance lnva and other substances were deposited around volcanic Vjcntfi, thus causing conical formations. Next, masses of rock in the form of strata were forced up obliquely, one upon another, by a pressure tending in one direction. When exposed the ends of the upper masses of strata formed mountain ridges. Opposing pressure against the strata caused folds in the earth's surface. Mountains were ulko carved by streams out of; raised sea-beds. l The old idea that the enrtli was a slowly coolinc mn.-is. said the lecturer.! lmd been displaced by a new theory. I that the interior of the enrtli was cool.i but that the surface was in a state of! upward ami downward oscillation. Adjacent masses of the earth's crust were believed to be in a state of balance, probably on a tnikstrata of heavy liquid.! sonic 7l! miles below the surface of thcl enrtli. Streams carried substance from] one mass to another, and caused ! the rising of one mass and the! sinking of another, ln time tlie rising mass would cease rising, because of outweighing the other mass. Thus were provided the pressures which caused mountains to be formed. At the conclusion a hcartv vote of thanks was accorded the lecturer.