148 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Color. While it has been shown that marine conglomerates are 
sometimes ferruginous, the remarks of Russell and Willis already 
noted tend to show that such rocks are not, as a rule, highly colored. 
Lacustrine sediments have also been shown to be usually free from 
red color. The evidence brought out with reference to estuarine 
deposits is insufficient to make any general statement; they are, how- 
ever, often considered to have a tendency toward a red color. Some 
of the fluviatile deposits described are shown to have highly colored 
red or purplish zones. Strahan, speaking of the characteristics of 
continental formations, says they have a common tendency to a red 
color (Strahan, p. 143-144). Crush-conglomerates, being induced 
as secondary structures in rocks already formed, partake of whatever 
color the parent rock may have possessed. Glacial conglomerates, 
as a rule, appear not to be highly colored, though the Australian 
boulder-beds are described as containing reddish brown members. 
Red color is therefore not a distinctive characteristic of any particu- 
lar type of conglomerate formation, but it may be said to be more 
common in the fluviatile and perhaps in the estuarine types than 
among the other kinds of conglomerate. 
Bedding. Marine formations have been shown to possess on the 
whole the best developed and most uniform bedding; while glacial 
formations exhibit the least developed and perhaps the most irregular 
stratification. Lacustrine and estuarine formations tend to resemble 
marine formations, while fluviatile deposits may be well stratified or 
on the other hand may so closely simulate heterogeneous glacial accu- 
mulations as to cause uncertainty as to their origin; witness the dis- 
cussion of. the Midland Pebble Beds of the Old Red Sandstone. 
Cross-stratification and lenticular masses of coarser and finer material 
are common in all these types but in the marine type the long axes of 
the lenses are more frequently parallel to the shore line, that is, to the 
original strike of the rocks, while in the case of fluviatile accumulations 
the long axes of the lenses are parallel to the courses of the stream 
threads by which they were deposited, that is, to the original dip of 
the rocks. All the water-laid deposits appear to increase in thickness 
and coarseness toward their source of supply. Other differences are 
cited by Strahan in his discussion of continental deposits. He states 
that the latter are not only unequal but alternate with erosion, so that 
fragments of one bed are included as pebbles in another; that they 
rarely contain marine organisms or such strata as usually compose 
marine formations, but that drifted plant remains are not uncommon, 
and that such liemstones as occur consist, when unaltered, of amor- 
