ANCIENT KOBUK GLACIER OF ALASKA 85 
About three miles south of the mission, the modern beach ridge 
approaches the sea-cliff. There are no true exposures of the material 
in the face of the cliff, but water-worn gravel like the present beach 
gravel, though probably of a different origin, occurs at several points 
up to 50 feet above sea-level. This is the seaward edge of a small 
plain about 75 feet above the sea. Less than a mile south there is a 
smooth ridge running inland; on its south side there is another 
broad flat plain extending inland half a dozen miles and probably 
two miles wide along the sea-cliff. Its altitude is about 75 feet above 
the sea; on the south it is bordered by another narrow smooth ridge 
running inland. A few very imperfect exposures on the sea-cliff form- 
ing the seaward edge of the plain show pebbleless brown carbonaceous 
silt, suggesting a lagoon deposit. It is evident to me that the depres- 
sions of a rolling upland have been filled with fine silt to a level which, 
possibly through uplift, is now mostly about 75 feet above the sea. 
Marine erosion has cut away a large part of these plains and the 
intervening ridges, producing a sea-cliff from 50 to 100 feet high, at 
the foot of which lies the modern beach ridge, generally 75 yards 
wide. There remains to discover the composition of the upland ridges. 
At about seven miles south of the mission there is a small lagoon 
winding about in the marshy floor of the valley whose mouth was 
originally below sea-level, the 75-foot silt plain above described not 
being developed here. Indeed, looking over the country south to beyond 
Cape Blossom, it appears that the smooth ridges generally rise to 
about 100 feet above sea-level and are separated by valleys of varying 
widths, generally coming down nearly to sea-level at the beach line. 
Inland as far as one can see there are no isolated hill peaks; nor, on 
the other hand, is there a suggestion that the valleys have been eroded 
froma plain. The topography suggests a constructional surface of a 
glacial type, not that of a terminal or lateral moraine, but of an 
undulating ground moraine. 
At about half a mile south of the lagoon, the sea-cliff, 60 to 100 
feet high, bisects a broad, undulating ridge which leads inland as do 
the others above described. Stiff blue-gray boulder clay abounding 
in beautifully glaciated pebbles and boulders (the latter generally 
gabbro or metagabbro), appears for nearly a quarter of a mile, rising 
from 10 to 50 feet above sea-level and overlaid by dark blue-gray and 
