1O 



PHYSICAL GEOGRAPHY. 



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Nova Scotia and Pennsylvania. His 

 ideal section represents the New 

 Hampshire rocks as granite at the 

 White Mountain centre, with gneiss 

 upon both sides, dipping on the east 

 towards Maine, and on the west 

 towards Vermont. The schistose 

 rocks adjacent to the gneiss in 

 Maine and Vermont are called &quot; Cam 

 brian.&quot; The Green Mountains of 

 Vermont are made out to be an 

 immense stratum of quartz rock, dip 

 ping westerly. These Cambrian stra 

 ta in their turn are flanked on their 

 outer sides by Silurian, and these in 

 their turn by Carboniferous rocks, in 

 the extremes of Nova Scotia and 

 Pennsylvania. 



Not to be misunderstood, I have 

 reproduced here Dr. Jackson s ideal 

 section. I shall attempt hereafter 

 to point out that in this idea there 

 is an important element of truth, 

 while many of the details are incor 

 rect. It is true, for instance, that 

 in the White Mountain neighbor 

 hood the older rocks make their 

 appearance. This view is derived 

 from the study of the formations in 

 the field, and is at variance with 

 the prevalent opinions of Amer 

 ican geologists, as held in 1868, 

 when our explorations commenced. 

 The quotation given in Chapter 1 1 

 shows that our first explorations 

 about Lisbon led to the conclusion 



