256 SURFACE GEOLOGY. 



gneiss of the Manchester and Deerfield range. We found the following 

 in pieces from three to four feet long : Sienite of Exeter, the most abun- 

 dant as usual, and twelve different varieties ; v/ell defined gneiss, flinty 

 slate, ferruginous mica schist, porphyritic gneiss (some blocks like that 

 of East Concord, others like the New Hampton rock, the feldspar very 

 abundant in double crystals), breccia of flint or indurated slates, sienite with 

 black patches, dolerite, gneisses like the Laurentian, green augite rock, 

 Concord gneiss, porphyritic gneiss with large garnets, saccharoid quartz, 

 gabbro like that of Gilford, sienite with feldspar, — perhaps labradorite 

 and fine gray granite. The following were found of less dimensions than 

 three feet, down to pebbles : Montalban schist with blotchy mica, trap of 

 various textures, granite like that of Barre, Vt., clay slate, andalusite 

 mica slate, jaspery quartz, slates like those of Portland, Me., fine-grained 

 reddish whetstone slate, Manchester gneiss, greenish sienite with por- 

 phyritic like parallel spots of gray quartzite, argillo-mica schist, reddish 

 porphyritic rock or sienite, gray garnet rock, Albany granite, red por- 

 phyry, white breciated quartz porphyry, and Tripyramid sienite or dio- 

 rite ; also, reddish Vv^eathering limestone, such as occurs in eastern 

 Maine. 



The most conspicuous and abundant of these materials came from the 

 sienite range extending between Dover and Exeter, and travelled from 

 nine to fifteen miles. A few of this class may have originated in a range 

 three miles nearer. Many of the slates came from the ledges inside of 

 the sienite. No andalusite slate is known to exist within twenty-five 

 miles. The Manchester gneisses have travelled certainly twenty miles ; 

 the others may have come from either a greater or a less distance. I know 

 of no porphyritic gneisses, like those occurring here, nearer than forty-five 

 miles in a north-west direction, while ledges sixty miles distant agree 

 with them exactly. The gabbro found at Gilford is in boulders, so that 

 I cannot certainly refer to their source. I find nothing that seems to 

 have come from a greater distance than the Tripyramid sienite, at ']J 

 miles. The porphyries may have come from greater or less distances, 

 possibly from the Ossipee mountains. Others of the pieces are like 

 rocks further north, but I cannot claim anything but the minimum dis- 

 tances. I do not specify many other distances that might be mentioned. 



I have assumed the north-west to be the proper direction of dispersion, 



