64 PHYSIOGRAPHY 



end they develop flats below the general level of the surface in 

 which they lie; and (3) that these flats are usually wider and lower 

 near the sea, and narrower and higher far from it. Fig. 1, PL XVII, 



Fig. 51. A valley much older than that shown in Fig. 46; Gray Copper Gulch, 

 southwestern Colorado. 



p. 64, and Figs. 51 and 52 show valley flats in various sorts of 

 regions. 



Streams which flow through flat-bottomed valleys are generally 



Fig. 52. A wide valley flat. Milk River, near Pendant d'Oreille, Canada. 

 (Drawn from photo. U. S. Geol. Surv.) 



