BULLETIN: MUSEUM 
MARINE 
OF COMPARATIVE ZOÖLOGY. 
LACUSTRINE 
ESTUARINE 
Matrix} Clean sands, fairly well as- 
_Rela- 
tions 
sorted, cross-stratified; angu- 
lar to rounded grains. 
Generally local materials, 
fairly uniform size, well 
rounded; may be scratched 
by shore ice, landslides, etc., 
but not faceted nor snubbed. 
May be ferruginous, but not 
usually highly colored. 
Stratification generally well 
marked. Cross-stratification 
often well developed; in the 
normal cycle finer sediments 
encroach upon and overlie 
coarser materials; sometimes 
local unconformities, irregu- 
larities, lenses, ete., but more 
regular along the original 
strike than along the dip; 
limestones in the series com- 
posed chiefly of organic re- 
mains. 
May be conformable or un- 
conformable; nothing espe- 
to 
Subja- 
cent 
Rocks 
cially distinetive of marine 
action. 
Similar to marine; 
perhaps less well sort- 
ed, less clean, and less 
well-rounded grains. 
Similar to marine, 
though perhaps less 
well sorted and 
rounded. 
Similar to marine. 
Conforms more 
closely with marine 
than with fluviatile 
deposits; in the nor- 
mal cycle coarse ma- 
terials encroach upon 
and overlie finer sedi- 
ments. Limestones 
or marls of the series 
contain of 
organ- 
remains 
fresh-water 
isms, 
Fine gravel and 
sand with much mud, 
unsorted, cross-strati- 
fied; angular to sub- 
angular grains, 
Local materials 
varying in size and 
not well sorted; sub- 
angular shapes on the 
whole; markings as in 
marine. 
Tendency to red 
color (?) 
Frequent and irreg- 
ular interbedding of 
coarse sands and finer 
materials; frequent 
cross - stratification; 
ripple-marked and 
sun- cracked surfaces 
with organic and 
other imprint mark- 
ings. 
Same as marine. 
as marine. 
y 
ie 
MANSFIELD: ROXBURY CONGLOMERATE. 
| 
; FLUVIATILE 
j 
| 
| II _ - 
Sands mingled with finer 
‘nd coarser material, not 
Well sorted, cross-stratified; 
‘Ngular to subangular grains. 
Generally local materials 
of all sizes up to masses of 
Several tons, generally sub- 
gular but varying from 
unded to angular; frag- 
Ments of one stratum in- 
tluded as pebbles in another 
Stratum of same formation. 
May be scratched by river- 
le action, landslides, etc., 
but not faceted nor snubbed. 
en 
Many not colored but per- 
aps tendency to red color. 
= 
Frequent alternation 
Coarse and fine beds; fre- 
Quent current markings and 
oblique lamination; frequent 
ocal unconformities; irregu- 
larities in thickness and 
Character, lenses, etc., but 
less regular along the origi- 
Mal strike than along the dip; 
limestones infrequent but 
Where they occur and are 
Waltered, they consist of 
amorphous carbonate of 
lime and not of organic re- 
Mains, 
FD 
Same as marine. 
CRUSH 
Unsorted auto- 
clastic fragments. 
Varying size and 
shape, angular to 
rounded, showing 
portions of crests 
or limbs of folds; 
fracture planes; 
tension cracks. 
Autoclastic frag- 
ments. 
Depends on par- 
ent rock. 
No true bedding; 
all traces of origi- 
nal bedding may 
have been de- 
stroyed. 
Pseudo - uncon- 
formity by over- 
thrust faulting or 
slickensiding. 
| 
| sometimes 
GLACIAL 
Heterogeneous of finer 
and coarser material, compact, 
angular grains of minerals and 
rocks; some fresh feldspar; some 
grains partially rounded and par- 
tially angular. 
mass 
Generally local materials, but a 
considerable proportion from dis- 
tant sources. Little, if any, as- 
sortment, all sizes up to masses 
of several tons. Pebbles faceted, 
rounded edges, snubbed ends, pol- 
ished and striated surfaces with 
striae generally parallel to long 
axis of stone but often showing 
two or more directions. 
Generally dark grayish with 
bluish and greenish tints, occa- 
sionally ferruginous. 
Till and 
formations 
corresponding ancient 
usually not bedded; 
obscure stratification 
and layers when separated show 
glazed and striated surfaces; some- 
times pockets, lenses and beds of 
coarser and finer stratified material 
with cross-stratification included 
in the unstratified mass. 
Fluvio-glacial material shows all 
gradations from no stratification 
to well-marked fluviatile type. 
Marine glacial boulder beds show 
well-marked stratification and al- 
ternation of coarser and finer beds. 
Rests on striated, smoothed, and 
polished surfaces of older rocks 
or older portions of the same for- 
mation. 
