1 82 SURFACE GEOLOGY. 



turned to one side, and was speedily crushed. Again : pieces of the rock 

 may be chipped off, as if the chiseUing fragment was not held down 

 firmly to the ledge, but had a jarring motion. Then there are the 

 LuNoiD Furrows. lunoid furrows. Vose describes them upon the 

 Green hills in Conway. Some seen on their north- 

 ern slope have axes running about S. 40°-48° E., 

 ^^' ^^' and are from one to four inches in diameter. A 



G section of one is given in Fig. 51. It appears that 

 the steep side. A, is always on the up-hill end of 

 ^-^i- the furrow. Four others were noted at the south 

 end of these same hills, upon a horizontal surface 

 ^ near the summit. They are figured in Fig. 52, are 

 Fig. 52. 1 1 inches long, 7 wide, and 4 deep, their direction 



being that of the dotted line, N. W. and S. E. These axes indicate the 

 course of the ice-movement. 



The origin of the lunoid furrow is given as follows by Dr. A. S. Packard, Jr., who 

 observed several of them on a hill near Goodrich falls in Bartlett, with the course S. 

 17° W., also on Mt. Baldface : * " It is known that the glacier is in constant motion, 

 advancing a few inches in summer, and then contracting in winter. Now imagine a 

 stone frozen into the ice, and thus acting as a gouge. Pushed onward, and then with- 

 drawn by the powerful hand of the ice-king, it soon wears this peculiar shaped hole, 

 then turns out of the rut, and catches again in some inequality of the rock, and makes 

 another lunoid furrow, or, perhaps, a series of four or five, often very regular in form, 

 though the distance between them may vary." 



The strias in New Hampshire vary considerably in their direction. 

 Before discussing the reasons for this variation, it will be proper to pre- 

 sent a list of all the observations of their occurrence that have been 

 recorded. They are all my own, except the few that are otherwise noted. 

 I have carefully reduced the compass to true courses. I hope to present 

 in the atlas a map showing these marks laid down with great care in con- 

 nection with the relief features of the ground. A very few observations 

 may be added for the adjoining territory, or what is included in our gen- 

 eral map. 



♦ American Naturalist, vol. i, p. 265. 



