DESCRIPTION AND NAMING OF SEDIMENTARY ROCKS 653 
B. INoRGANIC— 
1. Of chemical origin 
a) Calcareous rocks 
b) Ferruginous rocks 
c) Siliceous rocks 
d) Halides 
e) Sulphates 
f) Rarer types 
2. Of mechanical origin 
a) Uncemented 
b) Cemented 
It is highly doubtful whether new names under all these head- 
ings are needed. Whoever is not enamored of the emptiness of 
Hegelian dichotomy and its dread of intercrossing rubrics will rest 
satisfied with the use under A of such stand-bys as bacterial limonite 
(A 2), diatomaceous earth (A 3), or coal (A 4). Like granite, dio- 
rite, gabbro, these names mean something to the geologist who 
cannot be forever searching his Greek or Latin lexicon for prefixes 
and suffixes. Nor can any inventor of systems hope to force aside 
such terms as travertine (B 1a), clay ironstone (B 10), novaculite 
(B 1c), salt (B 1d), gypsum (B te). 
THE NAMING OF ROCKS UNDER AI AND B2 
Obviously, if such familiar names as onyx, sinter, uintaite 
gypsum are not readily replaceable, there must be a deeper reason 
even than their establishment in usage. The analysis of this reason 
results, it is believed, in the discovery that, preponderantly, such 
names have three great values: (1) they are simple; (2) they aid 
clear visualization; (3) they suggest a dominant mode of origin. 
Dissatisfaction with such terms as limestone and sandstone prob- 
ably arises, it may be unconsciously, from the failure of these 
names to meet the two latter criteria. 
Does not, then, the renaming of organic calcareous rocks and of 
“clastics” involve, as its pivotal motive, the use of a terminology 
which shall at least approach the suggestiveness of ‘“‘coal,’”’“‘tripoli,”’ 
etc.2 Furthermore, should not the new names be simple or at 
least readily comprehensible? Should they not aid visualization ? 
And should they not somehow unveil the complex of conditions 
under which a given rock originated ? 
