PANAMA LANDSLIDES.

Manawatu Herald, Volume XXXV, Issue 1165, 30 October 1913, Page 4

PANAMA LANDSLIDES.

THE CULEBRA CUT

The causes of the landslides, accompanied by upheavals, which have taken place in the Culebra cutting of the Panama Canal, provided the subject of a paper read before the engineering section of the British Association by Dr Vaughan Cornish recently (says the London correspondent of the New Zealand Herald). The deepest part of the canal, he said, is the Culebra cutting, and all geologists had decided that no landslips or other trouble could happen in digging it out. The cutting was made, and then came the strangest happening that could be imagined. Suddenly huge masses of the granite rock that formed the floor of the cutting bulged up and blocked the way. One of those bulging masses rose to a height of 9ft. in almost as many miuules. At the same lime, ac the edge of the cutting, a steady subsidence was going on. Dr Cornish likened the trouble to a curious flow of liquid going on deep down the cutting. Huge masses of eaith had been removed, aud something bad begun to work beneath. It had been known for a long time that there was a seam of coal below, but the coal was supposed to be firm and strong. Dr Cornish found out that when this coal began to rot it was apt to slide like a mass of tar. It never rotted until moisture came near it. When water got in it became rotten, and began to flow. Now, in the making of the Panama Canal huge areas of primeval forests had been cut down. This forest naturally absorbed the mighty rainfall of the district, aud gave it back to the air. So very little water penetrated to the lower depths. At least, it did not do so until the canal was built. Now that was all changed. Many square miles of the earth’s surface had been stripped of the trees that formed its natural covering, aud Nature had taken its revenge. The water had found its way down and touched the lurking giant below. It only needed a little to start it, but now the deep seated layer ot graphite or coal, or whatsoever it might be, had got that little, and was moving. The water that was moving it now began its work years ago. Dr Cornish expects the present work will have its effect for years to come, aud although the great cutting of the canal will be many times wider than was at first ex pected. it will have interruptions from time to lime from the upthrust. That will go ou for a year or two to come. When nature puts back the forest ou the stripped country, as it will do very soon, the underground flow will cease. It is not believed, however, that the upheavals will interfere with navigation. They will no doubt continue for a time, but, owing to the great width of th» channel, which in no place will be less than 300 ft., a navigable waterway will be maintained, any upheavals being dealt with by dredging. The effect of the entrance of water into the channel is doubtful, as while it might weigh down the bottom and prevent upheaval, it might increase disintegration, so that it will be necessary to await the outcome ot experience.