16 
FAIRBANKS AND RAMPART QUADRANGLES. 
ridge limiting on the northwest the valley of the Chatanika. A 
small area of the older rocks occurs also in the Rampart region.. 
Although the two groups have not been found in unconformable con- 
tact there was probably a long time interval between the deposition 
of the two, and the difference in the degree of their metamorphism 
is sufficiently great to constitute a metamorphic unconformity of 
stratigraphic value. The general strike is northeast and southwest, 
and the rocks wherever observed are closely folded. There are small 
areas of later rocks, probably not older than the Cretaceous ; slightly 
consolidated sediments of Tertiary age; and unconsolidated Pleisto- 
cene and Recent alluvial deposits. Granitic and more basic intru- 
sives are common in both of the older groups, and greenstones are 
especially abundant in them. Fresh volcanic rocks occur to a slight 
extent in the vicinity of Rampart and metamorphosed rhyolites are 
present in the area south of the Tanana. 
The following tabular statement is based only on reconnaissance 
trips and is therefore of a preliminary nature. The variety of rocks, 
the complexity of structure, and the paucity of paleontologic mate- 
rial in the areas studied render possible only the barest outlines of 
the stratigraphy. The areal distribution of the rocks is shown on 
the geologic map (PL I). The predominant lines of structure are 
well exhibited by the areal development of the rocks, and the forma- 
tion occurring in the White Mountains finds its continuation most 
probably in the rocks outcropping along the Tanana between the 
mouth of the Kantishna and that of Baker Creek. 
Provisional tabular statement of stratigraphy of Fairbanks and Ra*npart 
quadrangles. 
System. 
Series. 
Period or forma- 
tion. 
Lilhuiogic character. 
1 Quaternary 
\ Recent 
Stream gravel. 
Eocene 
glomerate, sandstone, and 
consolidated clay. 
Carboniferous 
Devonian and 
possibly older 
rocks. 
Silurian ( 9 ).. 
Permian o r 
Pennsylva- 
nian. 
stone and slate. 
Gray, greenish, and black 
shale with thin siliceous 
beds. 
Gray and blue, partly siliceous 
limestone, greenstone, 
quartzite, red, black, and 
green slate, conglomerates, 
and finer fragmentals and 
interbedded limestones. 
Chert, slate, greenstone, and 
limestone. 
Quartzite schist, quartz-mica 
Paleozoic 
Metamorphics 
Birch Creek 
schist. 
(Paleozoic or 
pre - Paleozo- 
ic.) 
and garnetiferous schist, 
greenstone schist, and crys- 
talline limestone. 
