-188 W. H. HOBBS LINEAMENTS OF ATLANTIC BORDER REGION 



rate maps which are engraved on a practicable scale have been sought. 

 The most satisfactory for the locality here under consideration is the 

 official map of the United States Geological Survey, which is engraved 

 on a scale of 1 : 7,033,000, or 111 miles to the inch. To form the base of 

 plate 45 the main hydrographic lines only of this map have been traced, 

 the culture being omitted. The official map itself and the official 

 map on the same scale printed in solid brown tones to indicate the 

 zones of different elevation should, however, be consulted and compared 

 with plate 45 for the additional evidence which they furnish. The last- 

 mentioned map brings out with especial clearness the plateau areas of 

 the region, owing to the fact that areas less than 100 feet, between 100 

 feet and 1,000 feet, between 1,000 feet and 2,000 feet, and above 2,000 

 feet are represented by shades of increasing depth of tone. Of especial 

 value also in the same connection is the plate printed by Powell to 

 accompany his paper on physiographic regions of the United States,* 

 since the borders of physiographic provinces correspond to important 

 lineaments. 



Lineaments have been extended on the map on the assumption that 

 their course is the trace of a vertical plane through the crust of the 

 earth — in other words, a great circle. For the longest indicated linea- 

 ment (the line H) the direction was assumed from the position of the 

 fall line at the two points, Baltimore and New York, and other points 

 on the great circle determined by location first of the vertex, then of 

 other points by the formulas used by navigators in great-circle sailing. 

 For the meridional series, with the exception of the long Hudson- 

 Champlain line, which is a great circle, the lines of the series are loxo- 

 dromes. For the direction given these lines vary but little from great 

 circles. This was found by trial to be true also for the northwest-south- 

 east series on the map, owing to the fact that the medial line of the 

 polyconic projection is far to the west. 



The dominant Lineaments 



the meridional series 



Connecticut line. — Before searching the map at random for the indica- 

 tion of earth lineaments it will be well to note whether prominent lines 

 determined for the smaller areas studied or indicated by the hydrog- 

 raphy of Massachusetts and Connecticut appear to extend beyond the 

 limits of these areas. Within the Connecticut area the direction which 

 is perhaps most strongly brought out in the drainage is that which 

 trends north 5 ± degrees east. This direction of earth lineaments was 



* The physiography of the United States, 1896, pp. 65-97. 



