136 ROSS ON PARALLEL LINES OF ELEVATION. 



tion of zones Nos. 4 and 5 with accuracy, and as I had not seen it 

 until I had become convinced from observations of other parts of 

 these zones that they must intersect each other at the Azores, in 

 the precise directions which they are there represented as having, 

 I was pleased to find that figure in Dana's Manual of Geology, 

 made without any thought of the zones of parallel lines of elevation, 

 but simply by observing the facts of the case, thus well illustrating 

 the correctness of the conclusions to which I had come by in- 

 duction. 



The axial line of a subzone sometimes becomes volcanic where 

 intersected by the axial line of a later zone ; thus where the axial 

 line of zone No. 1 intersects the subvenes of zone No. 4 on the 

 east of Asia, we find on one side of the axial line of zone No. 4 the 

 volcanic Peninsula of Kamtschatka, and on the other side the 

 volcanic Peninsula of Corea, and the more distant subzone of 

 which the axial line passes through the volcanic islands, Formosa 

 and Luzon. Where the axial line of zone No. 2 intersects the New 

 Zealand subzone of zone No. 5, that subzone is also volcanic. 



The forms of the craters of volcanoes seem to be largely deter- 

 mined by the lines of fracture, and these are determined by 

 the lines of elevation ; hence it follows that the forms of the 

 craters of the volcanoes of any group have a striking similarity 

 to each other, and resemble those of other groups, in proportion as 

 the producing causes, the intersections of axial (and related) lines, 

 are similar. The longer axis of a crater is found, not in the line 

 of the volcanoes, that is the older of the intersecting axial lines, 

 but in the later axial line (or parallel to it). Thus the Latin line 

 of volcanoes (Etna, Stromboli, Vesuvius, &c,) is in the axial line 

 of zone No. 6, the Sardinian, and has the major axis of its 

 volcanoes parallel to the axial line of zone No. 2, as these axial 

 lines intersect each other here. Where the axial lines of three 

 zones intersect each other as at the Hawaiian Islands, the result is 

 more complicated, but governed by the same law. Thus Kilauea 

 in Hawaii (the more important of the two active volcanoes in that 

 group) has its major axis in the line of zone No. 5 — the most 

 recent of the three intersecting zones, — while the extinct volcanoes 

 of this group have their major axes in the lines of zone No. 6 (an 



