136 ALASKAN MINERAL RESOURCES IN 1906. 
beach has traveled a shorter distance from its source and has been 
less subject to stream and wave grinding. 
In the third beach, then, irrespective of any greater differences 
which may have occurred in the meantime, we have definite proof 
that the land now stands not less than 79 feet higher than it did when 
the beach formed the coast line. Further evidence of elevation, 
though of lesser amount, is furnished by marine shells taken from 
various shafts between the second and third beaches. Such shells in 
an almost perfect state of preservation are found on Center Creek 
and suggest that in that locality they accumulated in comparatively 
quiet water. They occur in gravels 32 feet below the surface and at 
an elevation of about 20 feet above sea level. Numerous marine 
shells from Otter Creek were obtained at approximately the same 
height above sea but at a depth of 50 feet below the surface. They 
are in a good state of preservation. 
As a rule the deposits of the beaches and of the tundra in general 
are frozen from to]) to bottom, but there are places where this is not 
the case. One such area is located near the intersection of the third 
beach and Hotyoke Creek and has caused difficulty in working the 
Bessie Bench claim because of the large amount of water circulating 
through the gravel. The boundary between the thawed and frozen 
ground was here located by drilling, and care was taken not to bring 
the workings too close. Thawed ground is in some places overlain 
by frozen ground and here and there is underlain by it also. The 
reason for the presence of unfrozen areas is not entirely understood, 
but they are probably due in part at least to the circulation of water 
through the gravel. 
These old beach lines indicate periods of temporary stability in an 
intermittently advancing or retreating coast line. It is possible that 
they mark the limits of encroachments of the sea at different peri- 
ods, since in the case of the beaches mentioned the sea at the time of 
their formation was cutting fragmental deposits previously laid down. 
It is evident that if a sea floor gently sloping away from the land 
were gradually and uniformly raised, the beach line if affected by the 
elevation only would slowly move seaward, and that the beach depos- 
its would be continuous from the time when elevation began till it 
ended. Such does not appear to have been the case on the Nome 
tundra. 
The coast was not raised uniformly, and the upward movement may 
even have been interrupted by periods of depression. Nor are the 
tundra accumulations due to the work of the sea alone. Kivers and 
ocean both took part. Such streams as the Nome and Snake were 
already well established and spread their loads of loose material over 
the marine sediments at their mouths, carrying the shore line seaward 
and building up the lowland deposits. It seems probable, too, that 
