176 Amber ; its Origin and History. [ April, 
hitherto it has been proved here quite as little as at other localities 
on the north coast, where it exists at a considerable depth. 
The trough has evidently been formed by the upheaval of its 
two sides, and it can easily be shown when this commenced, and 
that it continued slowly. ‘This is taught us by the clay-bed (Fig. 
III., 2, 3.—2), already mentioned as occurring in the “ Quartz- 
sand” of the lower deposit, and as possessing a thickness of from 8 
to 10 feet. It has exactly the same extension as the trough; it 
does not, however, belong to its infilling, but lies under it, forming 
a part of its base. Together with the “Quartzsand” it possesses 
the same thickness as the latter assumes, where it alone forms the 
lower division of the formation. It therefore follows that the up- 
heaval of the sides began at a time when from 15 to 17 feet of 
“Quartzsand” had been deposited, and that while it continued, 
“Quartzsand” was thenceforward deposited only in the upheayed 
area; the resulting trough, however, was immediately covered with 
the mud, which is now hardened into a clay-bed. Where the clay 
is mixed with sand, it is not the “ Quartzsand,” but the fine Mica- 
ceous sand, which, as we shall see, forms the principal constituent 
of the infilling of the trough. This clay-bed, which I shall call the 
lower, because two others follow above it, belongs therefore, accord- 
ing to its situation, to the lower stage of the formation ; according 
to its origin, however, it belongs to the middle stage, and thus it 
connects in the most intimate manner the two divisions, one with 
the other. 
The materials which fill the trough (Figs. II., III., B 2) are of 
three kinds; namely—Clay, Sand, and Browncoal; but the first and 
the last occur only here and there, and the Sand (Fig. I1I.—+) 
must be considered the most important deposit in this series. It 
is composed of fine quartz-grains with an admixture of numerous 
small flakes of Mica and small bright-green granules of Glauconite. 
At the same time it contains many pieces of coal, partly as powder 
or small particles, and partly as large tree-stems. The first form 
the layers and nests, which give to a section of the sand a brownish 
striped appearance. I have, therefore, called this deposit the 
“Striped Sand,” and it is absolutely peculiar to the Prussian 
Browncoal-formation as a glauconitic Micaceous sand. It is, how- 
ever, on that account particularly remarkable, because it contains 
Amber, which occurs, not indeed so abundantly, nor yet in one precise 
layer, as in the Amber-earth, but still im tolerable richness as nests 
in the brown stripes, and with small pieces of coal. As this Amber 
comes from a much dryer stratum than the blue “ Amber-earth,” it 
may be distinguished both by its external appearance and its greater 
solidity ; and it is on that account more highly valued than that 
from the latter deposit, which, if it dries in the open air, becomes 
eracked and shivered. 
