THE PANAMA CANAL 



169 



ever, no one who has served on the canal 

 would try to make a definite prediction. 

 A picture of this slide before the water 

 was let in is shown on page 146. 



Gold Hill is a hard trap rock, with a 

 volcanic neck extending down to an un- 

 known depth, and is there to stay. On 

 either side of it, however, the strata were 

 very much disturbed and slides have oc- 

 curred of all kinds of material, both clay 

 and rock. The slides on the north side 

 are nearly all of soft rock. 



Colonel Gaillard, who had charge of 

 the work in Culebra Cut, never knew, 

 when he returned to work in the morn- 

 ing, that tracks and shovels would be 

 found as left the night before. He strug- 

 gled with the cut for six long years, until 

 it was practically completed, but finally 

 broke and died under the strain. 



Two distinctive kinds of slides are en- 

 countered in Culebra Cut. In one case 

 the entire body of material moves prac- 

 tically on an inclined plane, this plane 

 being sometimes rock, sometimes clay. 

 The Cucaracha slide is of this character 

 and is called a true slide. 



In slides of the other; character, the 

 first indication is a crack, in the bank, 

 sometimes 300 or 400 feet back from the 

 edge of the cut. This crack or break 

 opens, and the ground there will often 

 settle down before it does at the edge of 

 the cut. When the general movement 

 comes, the bottom of the cut comes up. 

 Steam shovels have been lifted by one of 

 these slides as much as 18 feet, with the 

 tracks hardly thrown out of alignment. 



EARTHQUAKES AND THE CANAL 



One of the great arguments against a 

 lock canal at Panama was the earthquake 

 argument, which prophesied that the 

 locks would inevitably be destroyed by 

 earthquake shocks. The picture shown 

 on page 179 is the answer to that argu- 

 ment. It shows the famous flat arch in 

 the now ruined church of Santo Domingo 

 in Panama City, which has stood there 

 for more than 200 years. The existence 

 of this old and apparently unstable struc- 

 ture is a proof that Panama is free from 

 serious earthquakes. 



An examination of this arch, taken in 

 connection with the fact that it has stood 



for the length of time it has, seems to 

 warrant the conclusion that Panama has 

 been more free from serious earthquakes 

 during the time in question than Tennes- 

 see, Missouri, or Arkansas, when it is re- 

 membered that Reel Foot Lake, in Ten- 

 nessee, and the "Sunk Lands," in Mis- 

 souri and Arkansas, along the basin of 

 St. Francis, were formed during an earth- 

 quake in 181 2, a little more than a cen- 

 tury ago, while this structure has stood 

 for more than twice that period. 



Panama has been visited by a few 

 earthquake tremors lately, one of them 

 being of sufficient intensity to cause vases 

 to fall from shelves, but careful examina- 

 tion of the locks failed to show the slight- 

 est cracks in the masonry, and the dam 

 showed no tendency to settle or change 

 its form in any way whatever. The cen- 

 ter of the disturbances which produce the 

 tremors is usually about 200 or 300 miles 

 away. I do not know where the center 

 of these last disturbances was, but when 

 the serious earthquakes occurred in Costa 

 Rica two or three years ago, only slight 

 tremors were felt at Panama. 



While I was away, in November, my 

 wife wrote me that there had been an- 

 other little earthquake since I left. She 

 was upstairs and had a Jamaican woman 

 sewing at the time, and just as the house 

 commenced to shake the Jamaican wo- 

 man fell down on her knees to pray. 

 While my wife believes in the efficacy of 

 prayer, she told the woman that the best 

 place to pray during an earthquake was 

 outside. The advice is thought to be 

 good. 



THE GATUN LOCKS 



All the essential features of the Gatun 

 locks are situated on rock. It is a soft 

 rock and was called indurated clay in the 

 first description of it ; but people did not 

 understand what indurated clay meant, 

 and so the name was changed to argilla- 

 ceous sandstone. 



This stone is solid and makes a good 

 foundation when not exposed to the air. 

 If so exposed, however, it acts like shale 

 and goes to pieces. In making an exca- 

 vation for the locks and as soon as grade 

 was reached, the foundation was imme- 

 diately covered with concrete, thus re- 



