1868. | Amber ; its Origin and History. 181 
in north-western Samland, and forms a covering of from 5 to 20 
feet in thickness, spread regularly over all older deposits. 
The destruction of the Tertiary strata had commenced before 
they were overflowed, no doubt by means of the masses of ice which 
were driven against the deeper beds. On thawing, the ice deposited 
the débris and stones with which it was laden. This explains the 
great gravel-bed which often lies imbedded in marl, near the remains 
of the Tertiary strata (as in Fig. IV., near A and E «). Often, 
however, surrounded by Diluvial masses, occur large blocks derived 
from the uppermost beds of the Browncoal-formation ; they fell 
down by the destruction of the middle beds, and remain lying in 
the mud. Thus were large blocks of the older rocks washed away. 
In Fig. II. we see such removals, both in the east near Neukuhren 
and Wangen, as also westward near Georgswalde and Warnicken, 
—isolated remnants of the older beds being still seen projecting 
from their foundations. In Fig. LV., also, is exhibited on a larger 
scale the last-named coast district, where near A is seen one such 
remnant, and near EK the step-like fractured margin of the Tertiary 
beds. ‘These denudations, however, were also sometimes accom- 
panied by dislocations, which were caused by the pressure of the 
masses of mud and sand which were thrown on the older beds. One 
such dislocation is shown in Fig. II. in the district of Rauschen ; 
and near Rosenort on the west coast we have the remarkable case 
of the older Glauconitic beds being upheaved, and not only covered. 
by Diluvial masses, but having also the same beneath them,—where 
they appear to have been thrust by lateral pressure. 
In the deeper erosions occur marl and sand, not in a regular 
succession of beds, but thrust without order into each other, or 
heaped up against one another. Such a mode of arrangement 
cannot be explained in deposits from water; but they may never- 
theless have arisen in two ways. At one time the ice-islands of the 
diluvial sea abundantly destroyed again the deposits which they 
had themselves formed, and the gaps which thus arose were filled 
up with other material. Still more generally it happened that the 
half-floating mud was forced upwards, by the weight of the sand 
which was heaped up on it, to such points where this pressure was 
accidentally slighter; by these means the mud penetrated into the 
overlying sand, as may be seen in Fig. IV. near B; or the sand beds 
were heaved up and thus fractured, as the sand beds D have been 
heaved up through the marl. All these changes took place slowly 
and in shghtly agitated water. ‘The proof of that is found in the 
circumstance that the broken and transported masses of the older 
beds are often found very near the places where they were detached ; 
and great deposits of Tertiary sand are found with the ordinary 
Diluvial sand in the Diluvium, having been derived from the 
denuded portions of the Browncoal-formation, 
