INTRODUCTION. 



Middlesex county is very irregular in outline, com- 

 prising an area, roughly approximated, of 830 square 

 miles. On the north it borders upon the New Hampshire 

 line, an extreme point in Dracut reaching to latitude 

 42 44' 12", on the east it extends (in Maiden) to longitude 

 71 54' , closely approaching the sea coast ; on the south, 

 it touches lat. 42 9' 30" (Holliston) ; and extends westward 

 in a single tier of towns to long. 71 1' 30" (Ashby). 



The highly diversified character of the county may best 

 be seen by a glance at the accompanying map and key. 

 The Merrimac river passes through the north-eastern 

 section, and the Concord through the centre, while all 

 portions are abundantly watered by numerous smaller 

 rivers and creeks. There are one hundred and thirty- 

 seven ponds, some of them of considerable size ; numer- 

 ous swamps of greater or less extent ; and salt marshes 

 along the tidal streams. The surface is very uneven, 

 Prospect Hill, Walthain, reaching a height of 482 ft. ; 

 Eeservoir Hill, Lincoln, 395 ft. ; Goodman Hill, Sudbury, 

 415 ft. ; Eeeves Hill, Wayland, 410 ft. ; Pegan Hill, 

 Natick, 408 ft. ; Nobscot Hill, Framingham, 602 ft. 

 The general elevation gradually rises to the highlands of 

 Townsend and Ashby, culminating in Mt. Watatic, a 

 granitic mass, 1847 ft. above the sea level, the highest 

 land in the county. 



The geological ages represented in Middlesex county 

 are three, viz. : 



1. The Cambrian, with slates and conglomerate; it 

 includes the comparatively low land within four to six 

 miles of Boston. 



