Davis — Terraces of the Westfield River, Mass. 87 



behavior of a river similar in volume to that of the present 

 Westfield than with the behavior of a much larger river. 



The fourth terrace in the Fochassic reentrant is caught on 

 a ledge of loose-textured sandstone, J, that stands forward from 

 the first small reentrant in the higher terraces. The ledge is 

 not directly exposed, but abundant angular fragments of pebbly 

 sandstone are found in the apex of the blunt cusp on the terrace 

 front. This terrace is believed to be the one that runs forward 

 in a long sweeping curve to the apex of Brown's spur ; but it 

 has not been followed all through the bushes and some details 

 of its form may not be shown in the figure. 



The divergence between the eastward course of the third and 

 fourth terraces, G and F, is highly significant. The third scarp 

 was cut a quarter of a mile back of what is now the apex of 

 Brown's spur, because at the time of the third northward swing 

 of the river, its channel had not been worn deep enough to 

 catch upon the summit of the ledges in the spur. But at the 

 time of the fourth northward swing the river had eroded its 

 plain to a lower level, so that it was held by the topmost ledge. 

 The fourth terrace, therefore, could not be cut so far back as 

 the third ; it makes a long sweep forward from the Fochassic 

 reentrant to the apex of Brown's spur and leaves a rather broad 

 plain between its scarp and that of the third terrace. It is per- 

 fectly evident that this arrangement of the two terraces was not 

 due to any decreasing strength on the part of the river, but to 

 the constraint imposed upon its wandering by the ledge at F. 



11. Ferr-ifs spur. — Below the fourth terrace, J-F, come 

 several others, which run forward to the rounded front of 

 Ferry's spur, K, K', where several blunt cusps are determined 

 by ledges of very friable sandstone that would hardly be seen 

 but for cuts made by the road and the railroad. This item is 

 of importance, for it shows that certain ledges which are strong 

 enough to defend a terrace are not always bold enough to keep 

 themselves in sight. After having done their duty in fend- 

 ing off the river, they strategically weather under cover and 

 thus ambush themselves again beneath a thin sheet of their 

 own waste mixed with creeping drift from the terrace they 

 have protected. It is possible that another example of this 

 kind may be found in the well defined cusp, Y)'" ^ of a low 

 terrace in the reentrant between Frospect hill and Brown's 

 spur ; it seems at first to be only the free intersection of two 

 curves, for there is no sign of a ledge at its base and there are 

 no angular fragments of sandstone by which the presence of an 

 ambushed ledge is sometimes revealed. A little digging or a 

 boring with a soil auger would suffice to determine this point. 



The indefiniteness of some of the terraces in the Fochassic 

 reentrant may be due to the discovery there of till underlying 



