A STUDY OF COBBLE ABRASION 



SIS 



Fig. 8. — Stage i, o miles, R = o 



Fig. II. — Stage 4, 2.18 miles, R= .130. 



Fig. 9. — Stage 2, .31 miles, R= .053 



Fig. 1 2 . — Stage 5 , 5.12 miles, i? = . 1 70 



Fig. 10. — Stage 3, .91 miles, R= oc, 



Fig. 13. — Stage 6, 14. i miles, R— .2^0 



