DESCRirXIOX OF MATERIAL USED 151 



G. Chesley gravel but containing a considerably larger pro- 

 portion of sand. 



In the easterly part of Durham are found extensive deposits 

 of an argillitic, quartzite rock, having much of the appear- 

 ance and many of the qualities of the traps. These deposits 

 occur all the way from Dover on the north to Stratham and 

 Newfields on the south. They form the whole, or at least a 

 large part, of the bed of Great Bay, and at various points 

 along this waterway, water-worn pebbles of this rock may be 

 shoveled up in considerable quantity at low tide. This was 

 the rock used upon section 12. It is the same that is em- 

 ployed by the city of Dover for macadamizing its streets, 

 except that there it is taken from a quarry. It is hard — easily 

 scratching glass — tough and compact. Like tlie traps it 

 breaks up easily along seams and joints into manageable sizes 

 when attacked in the quarry with dynamite, and is thus fitted 

 with comparative ease for the crusher. It breaks a little too 

 much on the slatey line to compare with the best traps, but 

 like them possesses good wearing and binding qualities. 



In many parts of Durham near Great Bay are found banks 

 of earth mixed with fragments of this same rock. It is not 

 then water worn, neither do we find it in small pebbles as on 

 the beach. It is simply earth and fragments of stone varying 

 usually from one to six inches largest dimension. This mix- 

 ture was tried upon section 10. 



It was at first intended to make the whole of section 8 

 alike, but when the available quantity of material was found 

 deficient, ten feet at one end of the section was set apart as 8a 

 and filled in with the screenings left over from the other sec- 

 tions. This coarse sand was thoroughly wet and rolled and 

 every effort put forth to consolidate it into a hard and durable 

 road surface. In truth, it made an excellent road for some 

 time, and could hardly be distinguished from the macad- 

 amized section adjoining for several months. Upon the bal- 

 ance of section 8, marked Sb, an attempt was made to have a 

 complete macadamized road constructed out of gravel. The 

 gravel was screened, sorted, put on in layers, the coarser at 

 the bottom, and each layer rolled as is usual in such construc- 

 tion. The two obvious obstacles to success in employing this 



