111 
the Waverly House, although there are plenty of ledges on its 
course. It is quite possible, however, that it passes under the 
street, in front of the Waverly House, as far as Valley Deach. 
It is perhaps possible, also, that this dike cuts 4 and 5, but 
more probable that they end before reaching it. On crossing 
the beach east of the Pacific House, this dike is seen cutting 
through the first ledge, near the road. Its characters are 
unchanged ; but in erossing the beach it is evidently jogged or 
shifted to the south about 25 feet, as if a transverse fault inter- 
vened (see map). 
Gun Rock, with its broad surface of bare melaphyr, is an 
uncommonly favorable point for the study of dikes. As 
already pointed out, it embraces two dikes (3 and 5) of the 
first system and five dikes (9—18) of the second system. 
Beginning on the west shore we have first the double dike (5) 
in a fissure about five feet wide. About 23 feet north of this 
begins the series of small dikes supposed to be the extension of 
the large dike (9) on Long Beach Rock. The following suc- 
cession is readily made out :— 
(1) Diabase, 0.5 feet. Separating melaphyr, 2 feet. 
(2) "M XO A 10 n tara 
(3) ч 80 ү gius 
(4) М O e Wi MEL 
(5) " TOREM "T М uu 
(6) bs ко" 
9 feet. 11 feet. 
Some 75 feet farther north, at the base of the steep slope, is 
the extension of 10; and about 100 feet of melaphyr separates 
this from 11, which hades N. 10° and, passing under the house 
at the top of the cliff, reappears оп the east side of the ledge, 
and again in the same direct line on the ledge east of Gun 
Rock, where it cuts the double dike of the first system (Fig. 
14). The intersection is clear and well exposed; and, so far 
as one intersection can, it establishes the relations of these two 
