Some Engineering Problems Of The Panama Canal In Their Relation To Geology And Topography

ENGINEERING PROBLEMS OF PANAMA CANAL. The temperature was so high that the hand could not be held at the mouth of the larger openings for more than a second or two, and when withdrawn was quite moist 8 lowing quite unmistakably the presence of steam or heated vapor. The sides of two ot the vents were incrusted both with white and yellow powdered material, the ye low appearing to be sulphur. What the white powder was I am unable to state. have observed this locality almost daily for over two weeks, and within the past four or five days there has been quite a change in two important characteristics. The temperature has increased and a pale-blue smoke, instead of steam, is now emerging from the vents. The odor of sulphuric acid, which was very marked when only steam was emerging, is fully as marked to-day. To give an idea of the temperature oi the larger vent I took a 9-inch brown manila envelope and held it at the mouth of the largest vent for three seconds, when it was totally destroyed, although it did not ignite in flame. 1 then took a piece of the white-pine covering of a dynamite box and held it for three minutes within the mouth of the largest vent and on withdrawing it it was completely charred, so that another three or four minutes exposure would probably have carbonized it completely. * * * I would respectfully recommend that the commission geologist be requested to make a careful examination and submit, as promptly as possible, a report on this matter, aa it is one of great interest to the work and undoubtedly concerna the safetv of our men who are handling dynamite. As you may recall, we have had premature explosions in the past on at least two occasions due to chemical heating of the rock and I am convinced that the material which I have described was hot enough to have readily fired dynamite at any time within the past three weeks. GEOLOGIST’S REPORT. In accordance with the above recommendation the writer made an investigation, and reported as follows: The marl shales, through which Culebra Cut extends, in the region opposite the ulebra railway station, have, from time to time, on exposure to the atmosphere become hot. The intensity of this heat Jias varied from noticeably warm to a tem- perature sufficient to readily char wood, without, however, causing it to burst into a llame The duration of this heating has varied in the several areas from a few days to several weeks. These slides are dark, thin-bedded, soft, and easily crumbled, and some oi the layers are largely fine basic tuff, or volcanic ash, loosely cemented by lime. Other beds contain more carbonaceous material, with some local partings of lignite an meh to a foot or more thick. The most easily weathered minerals of which these rocks are composed have been but little acted on by the atmosphere, and this, together with their composition, is evidence that they were derived from nearby volcanic mountains and deposited as a succession of thin beds in a shallow estuary of the sea which extended acrosè the Isthmus at that time. That this material was originally deposited in water is known from its clearly stratified condition; that the water was shallow is evidenced by fragments of fossil plants and thin beds of lignitic shale indicating swamp conditions, which are interbedded in it; and that the water was an arm of the sea is demonstrated by the fossilized marine animals, such as oysters corals pelecypods, and foraminifera, which it contains. The time when these conditions existed is known in geology as the early Tertiary or Oligocène period of earth history and the fossilized animals of that period have certain specific marks, by which the specialist may distinguish, them from animals of earlier and of later time. HEATING SUBSEQUENT TO DRILLING OR BLASTING. After exposure to tho atmosphere by drilling or Masting certain local areas of tills for- mation m the course of a few hours or days became warm, and as the heating goes on the carbonaceous matter in the shales gradually oxidizes and they tend to assume a gray