240 



synclinal axis, the beds on the west nppearinf;^ to be, so tar as 

 they go, a repetition in reverse order of those on the east. 

 This is the explanation which I proposed twelve years ago, in 

 my "Contributions to tlie geology of eastern Massachusetts," 

 and it is expressed in the section accompanying the special 

 map. This section shows an inverted syncline, on the east side 

 of which the beds, as tliey recede from the axis, round over to 

 a nearly horizontal position, as indicated by the observations in 

 the northern part of Melville Garden, west of the avenue ; 

 while on the west they maintain a high inclination until cut off 

 by a fault against the melaphyr. But few dips have been 

 observed west of the slate, and none so high as the section 

 represents. Hence the syncline, if it really exists, is 

 probably more completely inverted than it has been drawn. 

 Then, again, the repetition of the strata, as the map shows, is 

 by no means perfect ; and we note especially that it is impos- 

 sible to find on the west side as many beds of slate as are 

 clearly exposed on the east. Of the three beds which the map 

 shows on the west side, the second is based upon a single 

 outcrop and the third upon none ; while the conglomerate and 

 sandstone ])revent the extension of either of these far to the 

 north. In the construction of the map, it Avill be noticed, tliat 

 the interpretation was preferred in each case which, withojit 

 doing violence to the actual observations, is most favorable to 

 the synclinal theory. It can not be denied, however, that an 

 equally strong or stronger case can be made out for a 

 monoclinal structure ; and the latter appears to me now the 

 more probable view. 



Although this section, as a whole, bears a general re- 

 semblance to the Village and Deal's Cove sections, the pre- 

 cise correlation of the beds is a puzzling problem. The 

 much gentler dips and consequent broader outcrops must be 

 borne in mind ; for it may very well be that what in the otlier 

 sections is reckoned as a single bed appears here, through the 

 expansion of its outcrop, as two or more distinct beds. Great 



