THE PANAMA CANAL.

Stratford Evening Post, Volume XXXVII, Issue 61, 12 November 1913, Page 4

THE PANAMA CANAL.

A great deal of more or less sensational rumor has been set going regard-, ing the landslides on the Panama vanai excaations. Reliable information., however, it mov be taken, has been given; in a paper read before the British Association by Dr. Yaughan Cornish, who, described what has actually occurred. There have ben serious land movements; and will certainly be more, although Dr. Cornish thinks that stability will l>e attained in a few years and navigation should be safe in 1914, or about the time when the canal will be full of water and its locks completed. The landslides and upheavals occur in the famous Culebra Cut, which in all is nearly nine miles long. The greatest! deptli on the centre line in the Cut is 272 feet or forty feet above sea level. This bits already been readied, but water has not been admitted. The centre line of the canal follows a depression between the Gold and Silver Hills, and the rising ground on either side bringing the banks higher, the eastern face having a height above the canal bottom of 496 feet. The French comemncerl work about 18S3 and left off iii 1888 or 1889.' -Almost fromihe

beginning the French engineers were troubled by a continual sliding of material into the cut at Cucuracha. although the excavation only reached 45 feet dowm When they (eased work the slides ceased, largely because of the tropical vegetation which grew on the earth, strengthening it and protecting it from the weather. When the Americans took the work in hand in 1904 it was decided to widen the channel, which, moreover, was again widened from 1909. This widening necessitated cutting away the toe and side of the old Cucuracha slide, which soon began to slide again. . In 1907 the Cut was completely blocked. A> this time the depth of the excavation was hut little lower than the French left it. Since then it has been carried down 120 feet further, to, the final level,i and with each increase.in depth the 'difficulties have become .more.pro nounced. These difficulties are ap parently, it is stated by Dr. Cornish. of two classes. The rock in thf neighbourhood of the slides is partly in thin layers of soft volcanic origin interspersed with clayey lignite layers and broken up by upward intrusions of volcanic rock; the strata slop" ing towards the canal. When expos. ed to the air and, more particularly water, the, lignite'becomes rotten and tiro marl ' more clayey' in physical character. These weak and slippery layers are then deficient in strength and adhesion to the harder rocks below, and slow sliding takes place, the moving mass being dry earth and rock. Apart from slides a second diffi culty has arisen. owL.-g.to the canal bottom being upheaved in hump' twenty to thirty feet high. Thes< upheavals seem to be v. ( ;c- to weakness of the rock under the great pressure due to the banks above y.nd assisted by the effect of water percolating through the clayey and lignite seams To overcome this difficultv the slopes have been lowered to three horizonta 1 to one vertical, as against two horizon tal to three vertical at the beginningbut the slides still continue and seem likely to do so, although Dr. Cornish appears hopeful of ultimate stability. The upheavals are usually very rapid: in one case a rise of ten feet taking place in as many minutes. It is, how ever, reassuring to learn that the\ are not volcanic, and that the sulphurous fumes reported arise solely from the weathering of iron pyrites, a well-known phenomenon.