STRATIGRAPHIC CONFORMITY .AND UNCONFORMITY 291 
cation the structure is sensibly parallel and the deposition essen- 
tially continuous, continuity of deposition alone constituting con- 
formity, and of this continuity parallel lamination is a common 
but by no means a necessary or infallible sign. 
Again, these mutually exclusive structures are universal in the 
sense that the strata are everywhere either conformable or uncon- 
formable. And since true unconformity is absolutely inconsistent 
with continuous deposition, no mere irregularity of deposition, no 
matter how marked, can give rise to an unconformity. In general 
confirmation of this we have the fact that, so far as clearly recog- 
nized, each type of irregularity has, as we have seen, a designation 
of its own. In a later paragraph, additional names will be pro- 
posed for phases of conformity not always sharply distinguished 
from unconformity. 
SEDIMENTARY PROVINCES 
A. CONTINENTAL 
a) Terrestrial (continental surface) 
The deposition may be: 
1. Eolian 
2. Fluvial 
3. Lacustrine 
4. Glacial 
b) Coastal (continental margin) 
The deposition may be: 
1. Estuarine and deltal 
2. Littoral (shore) 
3. Marine (continental platform) 
B. OCEANIC (ABYSSAL DEPTHS) 
An exhaustive scheme is not aimed at here; but the purpose is, 
rather, to set forth the commanding importance, as a theater of 
sedimentation, of the coastal zone or province. Erosion is the 
normal geologic activity of the terrestrial province; and terrestrial 
' The growing tendency to designate land deposits as terrestrial instead of con- 
tinental meets the writer’s approval. ‘Terrestrial is clearly the more accurately 
descriptive term, since it does not exclude insular deposits, and does not include 
the deposits of the continental platform, which are as truly continental as any. 
