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DENVER & RIO GRANDE WESTERN ROUTE. 121 
pure to be worked profitably. The lowermost of these formations 
is the Weber shale, which lies directly above the Leadville limestone 
but which is so soft that it makes no showing at the surface. Above 
the Weber shale lies 200 or 300 feet of sandstone and shale that have 
a strong reddish tint, and above this for 1,000 feet or more the rocks 
consist mainly of light-colored sandstone separated by layers of 
shale. On account of this alternation of rocks the hillside appears 
to be ribbed horizontally by beds of white rock. 
As the railroad curves back toward the west the river cuts into 
the Leadville limestone. The rock is first seen near milepost 301, 
but it rises steeply and at the milepost is 30 feet above the track, 
Here the direction in which the beds of rock trend or strike begins 
to be affected by the northward plunge of the Holy Cross anticline,” 
so that the Leadville limestone, instead of becoming higher and 
Ficurn 31.—Anticline (at left) and syncline (at right). Perspective views and vertical 
sections showing the half-cigar-shaped mountains of hard rocks on the anticline and 
the canoe-shaped point of the syncline. After Willis. 
higher as the train descends the valley, dips down the stream, and 
before the train reaches Minturn the beds are below water level. 
The town of Minturn is built on a broad, flat valley bottom in 
which no hard rocks are exposed, but a mile below the station the 
same beds of rock which before were seen only 
Minturn. in the cliffs on the east form the mountain side 
Flevation 7,825 feet. on the west, showing that the beds of rock are 
opulation 298. (ee 
Denver 302 miles, swinging more toward the west than they do 
farther up the river. The red sandstone that was 
SO conspicuous above disappears on the right about the mouth of 
Gores Creek. This creek is a clear mountain stream that heads in 
the high peaks of the Gore Range on the east, some of which may 
be seen by looking directly up its valley. The stream is noted for 
“An upward bulge or fold of the | circular in outline it is called a dome. 
rocks is termed an anticline; if it is | The corresponding downfold is called 
long and narrow it is frequently called | a syncline. These folds are repre- 
an arch, but if it is short and nearly ! sented in figure 31. 
