SECTIONS EXPOSED IN HUMBOLDT OABON. 131 



Section H. — North bank of Humboldt River, 6 miles below Mill City. 



Feet. 



1. ^olian sands, with some gravel, irregular in thick- 



ness 



2. Marly clay, white, regularly laminated, jointed 15 Upper lacustral clays, 



3. Loam, sand, and gravel, massive medially, cross- ^m T l l 



stratified above and holow 12) 



4. Marls, regularly laminated, light drab ; to river... 10 Lower lacustral clays. 



37 



The medial gravels are markedly unconformable by erosion to both 

 the upper and lower lacustral beds. 



Section L. — South bank of Sumboldt River, Mill City. 



Feet 



1. Weathered marl, ffiolian sand at summit 2.5 



2. Marly clays, obscurely stratified, gray 3.0" 



3. Marly clays, white, laminated M. 



4. Marly clays, sandy, brownish, obscurely cross- 



stratified 2. 5 



5. Marly clay, white, laminated, jointed 9.0. 



6. Sand and gravel, somewhat ferruginous, fossilif- -^ 



erous 0. 5 



7. Sand, gravel, and pebbles, cross-stratified 5.0 



8. Sand and loam, massive, with pebbles 5. 



9. Sand and loam, obscurely andirregularly stratified- 4.0 I 



10. Sand and gravel, with ferruginous current 0. 3 I 



11. Sand, cross-stratified, fiue 3.oJ 



12. Marly clays, regularly laminated, ash colored. 



> Upper lacustral clays. 



Medial gravels. 



flarly clays, regularly laminated, ash colored, ) ^ , i i , 



..■',•.' . r , .' ' S Lower lacustral clays, 

 jointed, with some tufa at summit; to river 3. > 



40.8 



The tufa in the lower lake-beds occurs in uniform lenticular nodules, 

 in places forming a continuous layer an inch or two thick. Dendritic tufa, 

 in the form of mushrooms, occurs in the upper lake-beds above No. 5, near 

 where this section was taken. 



EXPOSURES IN THE CANOK OF THE TRUCKEE. 



The sedimentary deposits accumulated in Lake Lahontan are also well 

 exposed in its precipitous banks of the Truckee River from the point where 

 it enters the basin of the former lake, about 15 miles westward of Wads- 

 worth, to its termini in Pyramid and Winnemucca lakes. Above Wads- 

 worth the exposures are entirely of upper lacustral clays, which occur in 

 fragmentary masses on the sides of the canon in places where they have 



