2y6 The American Geologist. 
May, 1903. 
Prnf. N. II. WinchcU, 
Dear Sir: — Analysis of the samples of material for lime content 
gives the following results : 
No. I. (Natural) Lime (CaCOs) — i.co9% 
No. I. (Washed) Lime (CaCO.,) =0.975% 
No. 3. (Natural) Lime (CaCOs) =3.550% 
No. 4. (Natural) Lime (CaCO^) =5.207% 
No. 4. (Washed) Lime (CaCOa) =5.23 % 
Mincrological Laboratory. 
Charles P. Berkcy. 
These analyses indicate a considerable increase of carbonate 
of lime in No. 4 over No. 3 (from the roof oi the tunnel), 
due to downward leaching, whether washed or unwashed. It 
is quite probable that the feeble apparent attack of acid on No. 
4 when washed is in a large measure due to its fineness of 
grain. 
Microscopical examination of the loess (No. 3.) overlying 
the silt layer disclosed grains of several minerals found in the 
crystalline rocks, such as feldspar, hornblende, magnetite and, 
most frequent of all, quartz. These are from 10 to 100 times 
the size of the ultimate grains found in Nos. i and 4. 
8. The silt layer is very evident on the west side of the 
tunnel. Its fissured character has been described. After the 
tunnel had been extended further by Mr. Fowke, and an ofl:- 
set had been excavated toward the east, the characters at the 
inner end of the tunnel, in the east side, as described by pro- 
fessor Chamberlin, seem to show that the stratified silt layer 
actually does appear on the east side. These characters are 
mentioned and quoted in his words under No. 10.* 
9. There is no call for adverse coiument on Nos. 9 and 10, 
for the writer saw the same features. Those mentioned under 
No. 9 are particularly interesting as they show the wide ex- 
tent of the structure lines apparently controlled by stratification 
in the main loess deposit. They are probably more evident 
in situations near the Missouri river than in the sheltered 
angles, and therefore they apparently increase toward the 
east. Still, in the eastward oft'set tunnel cut by Mr. Fowke 
the material is wholly geest, and shows nO' horizontal structure 
lines like those seen in the loess of the main tunnel. The 
• Later examination shows that the eastward offset referred to is excavated 
entirely in the fine geest, with few residual limestone fragments. The vertical 
jointage described by Prof. Chamjjerlin pervades the whole mass of geest, both 
here and on the face of the ttinnel. 
