NOME REGION. 137 
conditions such as prevail along the southern coast of Seward Penin- 
sula to-day may have existed in the past and that the formation of 
lagoons shut off from the sea by sand bars, as may be seen east of Cape 
Nome and on a much smaller scale at localities like the mouths of 
Derby, Little Derby, and Cunningham creeks, may have taken place, 
and that these lagoons by subsequent filling may have piayed an 
important, though not the only, part in the construction of the Nome 
tundra. 
This idea of the formation of the ancient beaches implies that the 
land formerly stood at a lower elevation, but it is also evident that it 
once had a greater elevation, for the rock valleys of Nome and Snake 
rivers are lower than the third-beach line at the places where they are 
crossed by it, and are even below the present sea level. The rock 
floor under the present beach also may have been above sea level 
when it was produced; it was surely little if any below it. 
The formation of either of the old beaches was only an incident 
among the various changes which finally gave us the tundra as we see 
it to-day. A repetition of the same succession of events that led to 
the burial and preservation of the second and third beaches would in 
time add the present one to the tundra's treasury. From the geolo- 
gist's standpoint these deposits are neither unique nor unusual. The 
concentration of heavy minerals by ocean waves is a commonly 
observed phenomenon, and it is only the value of the concentrated 
material which in this case brings the deposits to notice and makes 
them remarkable. 
GLACIATION. 
One of the difficult problems of the region is to discover what effect 
the action of glacial ice has had in modifying the former topography 
and in transporting loose material. That the upper valleys of nearly 
if not all the streams flowing south from the Kigluaik Mountains, as 
well as some of the tributary valleys of Grand Central River and 
Salmon Lake, have been occupied by ice masses in very recent time 
is beyond question. The morainic deposits at the head of Nome 
River indicate that at least the upper portion of that valley was occu- 
pied by ice, and several of the eastern tributaries of the river have 
well-formed cirquelike amphitheaters at their upper ends. There is 
no evidence available to show that the peninsula, or rather the 
southern portion of it, has ever been covered by an ice sheet. On 
the other hand, all the evidence seems to oppose that idea if our con- 
ceptions concerning the rate of rock weathering are correct. The 
occurrence of monumentlike rock masses, due to weathering, on the 
hilltops or slopes is one of the noticeable features of the region, and 
it seems extremely improbable that they could have withstood the 
advance of moving ice or that they could have been formed since the 
