342 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
The closure completed in December, 1906, and the closure made the 
following spring were essentially similar in plan. Piles were driven 
across the break, as shown on Pl. VII, and upon these parallel lines 
of railroad were constructed. Two and in some cases three parallel 
tracks were thus provided, so that trains could be rapidly operated 
and run out over the break, crossing it and having ample switching 
facilities on the far side. 
When all was in readiness train load after train load of large 
stones were run out over the gap and dumped as rapidly as possible, 
the effort being to put in rock faster than the river could wash it 
away. A large amount of material was washed down the stream 
for a hundred and fifty feet or more and the bottom of the channel in 
which the large stone sank was rapidly cut. By carefully watching, 
however, and sounding so that the holes as they formed could be 
detected and filled, it was found possible to build up a broad low heap 
of large stone immediately under the railroad trestle. 
The chief difficulty was to secure a sufficient supply of stone fast 
enough to fill the gaps as washed out. In some cases it is stated that 
trains of flat cars loaded with stone were brought from a distance of 
400 miles. They came from quarries located not only on the Southern 
Pacific but also on the Santa Fe and San Pedro railroads. In fact, 
it is stated that even high-grade cut stone en route for building was 
requisitioned and diverted to fill the need. 
The stones used were as large as could be handled or pushed from 
the flat cars by a gang of men or by as many men as could get around 
a stone. In some cases the pieces were so large that it was neces- 
sary to break them by what are called “ pop-shots ” of dynamite laid 
upon the stone while it rested on the cars. In this way the stones 
were broken and then could be readily thrown overboard by hand. 
The scene at the closure of the break was exciting; train after train 
with heavy locomotives came to the place and the stones large and 
small were pushed off by hundreds of workmen as rapidly as the cars 
could be placed. While waiting to get out upon the trestle the larger 
stones were broken by the “ pop-shots.” The noise sounded like artil- 
lery in action. Added to the roar of the waters were the whistle sig- 
nals, the orders to the men, and the bustle of an army working day 
and night to keep ahead of the rapid cutting of the stream. 
As the rock heap rose gradually, it checked the river, causing it 
also to rise higher and higher and to cascade over the pile of stone. 
Riflles were caused and an undercutting of the lower slope or of the 
rock heap allowed it to settle and the stones to roll downstream. All 
of this undercutting and settling had to be made up and overcome by 
the rapid dumping of other large stones. 
It was necessary to raise the river bodily about 11 feet. As the 
water rose and became ponded on the upper side of the rock heap, 
