14 
Bulletin 65. 
MECHANICAL ANALYSIS OF THE “ FINE EARTH.” 
§ 29. The beaker ejutriation of the fine earth gave the follow- 
ing results: 
TABLE I.—MECHANICAL ANALYSIS OF THE FINE EARTH. 
SAMPLE. 
Hygroscopic 
Moisture. 
Temperature 
of Absorption. 
Water 
Capacity. 
Soil A. 
6.40 
15° 
51.05 
Soil B. 
4.50 
15° 
36.50 
Soil C. 
4.20 
15° 
44.22 
Soil D. 
5.90 
15° 
40.54 
Soil E. 
3.40 
15° 
36.84 
Soil F. 
3.50 
15° 
42.34 
TjoessSoil. Weld Co.. 
Loess Soil. ) 
Larimer Co. ) ' 
Red Soil. ) 
Clay Soil. >. 
Red Beds. ) 
Coarse Sand. 
1.0 to 0.5 mm. 
Medium Sand. 
0.5 to 0.25 mm. 
Fine Sand. 
0.25 to 0.05 mm. 
Silt. 
0.05 to 0.01 mm. 
Dust. 
Less than 
0.001 mm. 
Clay 
by Difference. 
• 
Ignition. 
4.459 
5.392 
26.078 
19.527 
27.878 
8.314 
8.&51 
8.114 
10.147 
35.593 
12.386 
23.653 
4.582 
5.543 
7.318 
6.940 
20.518 
20.828 
27.633 
7.876 
8.887 
6.254 
7.197 
25.894 
24.748 
21.704 
6.013 
8.190 
7.070 
9.227 
29.947 
25.573 
16.642 
3.534 
8.007 
6.380 
7.409 
23.736 
30.604 
19.488 
5.552 
7.673 
1.172 
3.737 
45.707 
27.721 
10.565 
5.217 
5.881 
0.965 
2.073 
24.451 
49.714 
11.797 
4.567 
6.433 
4.411 
11.872 
27.943 
31.592 
13.793 
4.60C 
5.789 
THE MINERALOGICAL CHARACTER AND SOURCE OF THE SOIL 
PARTICLES. 
§ 30. The sand grains in the different samples consisted of 
quartz, feldspar and some flakes of mica. The quartz grains show 
plainly the deposition of oxid of iron upon their surfaces, in checks 
and depressions in the grains. The deportment of the sand, and 
more particularly the still coarser portions, warns us that we can¬ 
not conclude that the sand particles owe their origin to the red beds, 
because of their color after ignition, for there is enough organic 
matter coating the grains to cause blackening upon heating, and 
this may account for the presence of the iron oxid which becomes 
evident upon igniting the sands. There is nothing distinctive 
enough, so far as I have observed, about the sand grains to justify 
one in asserting that they did or did not come from the juratrias, or 
Dakota sandstones, or are directly due to the breaking up of the 
granites. The presence of so large an amount of feldspar and mica, 
neither of which is present in the sandstones of these formations in 
such quantity, is strong proof that practically the whole mass is 
derived directly from the rock masses of the mountains which lie 
immediately west of us, and consists of granites, gneisses and mica 
schists. 
§ 31. While I believe myself justified in making the state-. 
