G. H, Williams—Norites of the “ Cortlandt Series.” 193 
Ih lie Mean. 
SION set aes o28 55°40 55°34 
ANT sO ies 2 1 ehiapa 16°31 16°44 16°37 
Her Ola. 5 se eae 0-69 0°85 Og Tn p 
Be O) see atam 5 GST T51 754 
Wi KO eS Ne lO 0:40 0°39 0°40 
Mo Oe ace) sale 5°05 5°05 5°05 
CAO arene a5? 7°49 75 
Nia Oe ce ae 20 4:03 4°06 
Ke @ eet nn 2:00 2°00 2°03 
HE OR aaa 4/0758 0°58 0°58 
99°55 99°73 99°65 
Professor Dana describes this rock as an augite-norite con- 
taining about equal proportions of hypersthene and augite. <A 
thin section in his collection marked (Mt. 20) the writer supposes 
to be the one alluded to in his description as it is the only one from 
this locality. This is, however, almost a typical norite with a 
large proportion of the usual reddish-brown feldspar, very 
typical hypersthene, and only occasional individuals of a green 
fibrous diallage and dark brown biotite. The percentage of 
lime in the analysis, after deducting what is necessary for the 
feldspar also indicates but a small proportion of augite. This 
section also shows considerable unstriated feldspar, which, from 
the analogy of No. 48 and the percentage of potash found in 
the analysis, may safe:y be assigned to orthoclase. A study of 
this section indicates that this analysis is very representative of 
the average norite of the Cortlandt Series. 
A more typical augite-norite or hyperite is to be found in 
specimen No. 69, of the Johns Hopkins University collection, 
which was collected from the same locality as the above. Here 
the proportion of both augite and biotite is considerably greater 
than in Professor Dana’s section. This slide is especially inter- 
esting from the fact that it exhibits, in both the hypersthene 
and augite, inclusions which the writer would without hesita- 
tion consider as secondary and identical as those in the Scot- 
tish rocks which Professor Judd rightly ascribes to schilleriza- 
tion. Side by side with these, however, are other inclusions in 
the feldspar which, like those above described, are original. 
No. 105 in the University collection from the road from 
Centerville to Verplanck, and a section, marked J, in ProfeSsor 
Dana’s collection from Craig’s place, one mile S.E. of. Peekskill 
are also admirable examples of the augite-norite. Both con- 
tain nearly as much augite as hypersthene. The former min- 
eral is distinguished from the latter by its green color, the 
entire absence of pleochroism, its highly inclined extinction- 
angle, the frequency with which it forms twins, and its com- 
