MANSFIELD: ROXBURY CONGLOMERATE. 1138 
epidote. The age of the conglomerate is not known because no fossils 
have been discovered in it (ibid., p. 62). 
As regards the origin of the conglomerate Helland argues (ibid., 
p. 63 et seq.) that the rock was deposited in separate synclinal basins 
and that the materials of which it is composed were derived from the 
surrounding mountains. In the discussion of their possible means 
of transportation he recalls the variety in substance and size of the 
pebbles, their unsorted and heterogeneous arrangement and their 
shape, which is rounded but nothing like the form assumed by beach 
pebbles (ibid., p. 70). Their formation as waste accumulated at the 
base of mountain slopes is considered unlikely because the pebbles in 
the conglomerate are not angular, the heaviest masses do not lie far- 
thest down and the materials of which they are composed are not sim- 
ilar (ibid., p. 71). Fluviatile or lacustrine origin may be assumed for 
the more sandy parts of the formation, for the deposited masses in a 
lake are usually more or less plainly divided into layers of sand and 
stones arranged according to the varying action of the currents; 
moreover, the pebbles rest on their surfaces that are nearest flat and 
the largest ones are deposited at the mouths of the rivers (ibid., 72- 
73). But a large part of the formation, including even one entire 
distriet, the Sulen Islands, is filled with pebbles that are not in the 
least like alluvial formations. On the contrary, they are most like 
the diluvial formations of the north European plain (ibid., p. 74). 
The lack of striated pebbles, the most prominent peculiarity of gla- 
cial formations, is important, but this fact does not exclude the pos- 
sibility of glacial origin, for it is often difficult to find striated pebbles 
in accumulations that are admittedly glacial. It must be remem- 
bered, too, that where the conglomerate is most like the diluvial 
masses the matrix is firm and fine grained so that the pebbles are 
more’ easily broken than removed, and their surfaces are seldom 
seen. When the matrix is sandy the conglomerate is more like the 
German “Diluvialkies” which usually has no striated pebbles (ibid., 
p. 75). Helland’s conclusion therefore is that the combined activity 
of ice, water, glaciers, and rivers seems to be best adapted for the pro- 
duction of such a varied formation as the conglomerate in question 
(ibid., p. 80). 
:—Alps. Along the northern base of the Alps extensive masses 
of conglomerate occur, the so-called “Schotter Conglomerates,” which 
are intimately associated with glacial deposits. Those in the Salzach 
region of Austria and Germany are described by Brückner. At 
Emetsham, at Hohenwart on the Alz and at Handenberg, the Schotter 
