430 STUDIES FOR STUDENTS 



4. Sorted into lenses and pockets rather than into definite, uniform, con- 

 tinuous layers. 



5. Constituents have a roundness superimposed on subangularity. 



6. Striae rare or lacking on pebbles. 



7. Thickness varies with irregularities in bed and shows a general tend- 

 ency to thin in one direction. 



8. Appreciable part of material foreign. 



9. Generally does not lie on bed rock, and contact below is not necessarily 

 sharp. 



10. Fossils worn, but may include unworn terrestrial forms. 



11. Likely to be found in the vicinity of glacial till. 



Fig. 8. — A fluvio-glacial deposit in Wisconsin (photograph by L. E. Wells). 



Fluvio-glacial deposits bear all relations in position to glacial 

 till. They lie over, under, or within the till, though they may also 

 lie out beyond the till in the form of outwash plains or valley trains. 

 Fluvio-glacial deposits are shown photographically in Fig. 8. 



LACUSTRINE DEPOSITS (nEAR-SHORE PHASe) 



In these deposits are the materials brought to lakes by streams, 

 cut from the shores by waves, carried and deposited by feeble 

 littoral currents, etc. The zone of deposition is one of frequently 

 changing conditions, due to changes in volume of streams, strength 

 of wind, direction of shore currents, shape of spits, bars, deltas, 

 etc. These deposits may be distinguished by the following char- 

 acters: 



