Iditarod pioneer., 1916-05-06
ALARMIST CANAL REPORTS
 CONTRADICTED BY BIOLOGIST

WASHINGTON March 11.-That the Panama canal will not be swallowed up by an earthquake in the future, and that the troublesome slides now being encountered will eventually be conquered and the great waterway made an unqualified success IS the opinion of Donald F. Macdonald, for merly canal geologlst, and now mining geol ogist for the United States bureau of mines
 Mir MacDonald who spent several years on the Isthmus making a careful study as to fraglity of the earth's crust, has just made an official report to the effect that while through seismic disturbance the whole Isthmus is rising at the rate of three feet very hundred years, this will not necessarily njure the canal. As far as he sees, 1t will merely mean a little additional expense in the dredging of the big waterway The cause of the rising, he says, is the sinking of the ocean bottom outside the Isthman shore waters. Every time there is little movement of the ocean bottom the Isthmus, to be in harmony, joins in. He also sug- gests that if the rising motion be rapid, then there would be serious danger for the canal but that from what has happened in recent geologic time it may be concluded that the canal is not in any appreclable dan ger from the instability of the Isthmisn land. The rising of the Isthmus, however, has been responsible for the many slides that have been encountered, ill that the motion of the ground has diSlocated and crushed the rocks leaving them weak and unstable.
 At any rate" said Mir Macdonald, "so far as the digging of the Culebra cut is concerned, these faults have increased the cost of the canal several million dollars
 "As to the slides Cuebra cut is a vast ditch that passes through many varieties of rock in the nine miles of its length. Some of these are weak and unstable, and where the slopes of the cut were steep and 100 to 300 feet high the weaker rocks crushed down to aatter slopes Whenever the slope got flat enough the sliding stopped. At no time did the engineering staff constructing the canal believe that the slides were menace to the ultimate completion and successful operation of the canal, in spite of the fact that at times they were some what troublesome They have made nee esSary the excavation of about 30,O0O,000 cubic yards more than was included in the first estimates for Cuebra cut, but they have not in the past and will not in the future endanger the ultimate success of the canal
 Mir Mcdonald calls attention to the fact that one is apt to forget that the great est variation of atmospheric pressure near sea level may be more than four million tons per square mile and that if the ad- Justment of atmospheric pressure, in a very large cave or mine, lags behind any quick increase in atmospheric pressure at the sur face, considerable strain may be added to the roof of such an excavation Dis cussng the real cause of the slides, Mir. Mcdonald declares that in many cases the immediate cause was the ovcrStecpneSs and height of the slopes, the blasting and other work attributable only to man. He adds that the geologic conditions were not suffi- ciently considered in the first plans for dig gng Culehra cut
 As the strength of the famous Gatun dam has been brought into question on number of occasions, Mir Mcdonald refers to it at some length. Tt was found that the Gatun rocks were relatively solid and compact end suitable for foundations for heavy structures However, some writers, even recently have affirmed that the Gatun rocks would soften into mud when Gatun lake filed and thus the locks and dam would sink their foundations and be dam aged or destroyed. Opinions of this sort spring from vivid imagination and not from facts.
 If the weight of Gatun lake is going to force water into the Gatun formation and cause it to soften into semi-mud that will q l0U inc Jam tO sink then all thp islands in Gatun lake and all the hills around it. which are of the same formation, should also have their bases softened the same way, and sink into the depths. Reports that the Gatun dam and locks are in any danger from sinking have not the slightest foundation on geologic data"