608 The American Naturalist. [July, 
GEOLOGY AND PALEONTOLOGY. 
Geology of Alaska.—In a report on the Coal and Lignite of 
Alaska Dr. Dall publishes some general notes on the Cenozoic geology 
of the Territory. In general, the sequence of rocks along the south- 
eastern coast where undisturbed is about as follows, in descending 
order : ; 
“1. Soil and Pleistocene beds.” 
“2. Brown Miocene sandstones, with marine shells, cetacean bones, 
and water-worn, teredo-bored fossil wood (Astoria group, Nulato sand- 
stones, Crepidula bed).” 
“3. Beds of conglomerate, brown and iron-stained, alternating with 
gravelly and sandy layers, the finer beds containing fossil leaves of 
Sequoia and other vegetable remains. (Kenai group, Nuga beds).” 
“4, Bluish sandy slates and shales, with rich plant flora, interstrat- 
ified with beds of indurated gravel, fossil wood, and lignitic coal (Kenai 
group).” : 
“5. Metamorphic quartzites and slaty rocks, with perhaps part of the 
lower Eocene (Tejon).” 
“6. Granite and syenite in massive beds, usually without mica and 
apparently in most instances forming the “ back bone” of the mountain 
ridges or islands, but occasionally occurring as instrusive masses, which 
have thrust up the metamorphic rocks above them into arches, crack- 
ing them, and filling the fissures. with the syenitic material. (“ Suma- 
gin granite).” 
The author correlates the Kenai group with the Oligocene of Euro- 
pean geologists. The beds overlying the Kenai conglomerates and leaf 
beds are undoubtedly Miocene. Mr. Dall concludes from a comparison 
of their fauna with modern forms that in Miocene times the waters of 
this region were warmer than at present. — 
The Pleistocene epoch is marked in Alaska, as in California, by — 
great changes of level, and by volcanic activity. To this period is 
assigned the ground ice formation which has been recognized in many 
places in the northern part of Alaska. This consists of solid beds of 
ice of considerable thickness, functioning as rock strata, which are 
covered by beds of blue clay containing remains of Pleistocene mam- 
mals, or by beds of alluvium which sustain a layer of turf, with ordi- 
nary profuse herbage of the region, or even small thickets of birch, 
alder, and other small Arctic trees. 
