620 W. H. TWENHOFEL AND F. T. THWAITES 



Percentage 



5. 6.83, transparent quartz, grains subangular to angular. 



6. 28.80, essentially no rounding. 



7. 19 . 27, no rounding, a little 'dolomite. 



8. 15-71, as No. 7. 



9. 3-47, as No. 7, with about 10 per cent dolomite. 



10. 25 . 84, this rectangle represents the glauconite present in the sample. 

 This sand was deposited some distance from the belt of constant wave- wash 

 as shown by its fineness and little rounding. 



C. Fine-grained sandstone from near base of the Jordan, Jeff Davis Rock, 

 Tomah quadrangle. 



Percentage 



1. 0.00. 



2. 1 . 78, transparent quartz, grains highly spherical and pitted. 



3. 10.00, transparent quartz, high sphericity, grains pitted. 



4. 6.45, transparent quartz, high sphericity, grains pitted, estimated 



5 per cent subangular. 



5. 18. 52, transparent qtiartz, with a few grains of limonite, grains well 



rounded and pitted, 5 per cent subangular. 



6. 50 5°, as No. 5. 



7. 11.29, transparent quartz, well rounded with a few angular grains. 



8. 1 .06, transparent quartz, 60 per cent subangular to angular. 



9. 0.40, transparent quartz, with a little clay, and dolomite, about 



5 per cent rounded, about 10 per cent aggregates of finely 

 divided quartz. 

 The assortment, rounding, and cross-lamination of this sand suggest wind 

 deposition. 



D. St. Lawrence sandstone, 2 mUes southeast of Norwalk, Wis., 50 feet below 

 base of Oneota. Contains marine fossils. 



Percentage 



1. 0.00. 



2. 0.00. 



3. 0.00. 



4. o . 40, transparent quartz, grains rounded. 



5. 0.36, transparent quartz, rounded and subangular grains, estimated 



10 per cent muscovite flakes. 



6. 0.60, as No. 5. 



7. 12.00, transparent quartz, angrilar grains, occasional muscovite 



flakes and limonite grains, a little dolomite. 



8. 17 92, transparent quartz, nearly all grains angular. 



9. 68.72, transparent quartz, 75 per cent aggregates, no rounding 



whatever. 

 The last rectangle does not express the actual facts as it is composed of 

 grains varying from .074 rhm. in diameter to dimensions fully one one- 

 hundredth of that dimension. This sand was deposited beyond the zone of 

 constant wave-wash. 



