MEMOTRS 
OF THE 
CARNEGIE MUSEUM. 
WOlb, 1k NO. 5. 
THE TERTIARY OF MONTANA. 
By Eart Dovuauass. 
IntTROpUCTORY REMARKS. 
It has long been the wish of the writer, to prepare a memoir, complete as it is 
possible to make it, on the Tertiary formations of western Montana, the object being 
a restoration, so far as is practicable, of Tertiary times there, to accumulate data so 
that fairly accurate mental pictures of the conditions at the different periods may 
be obtained. It is not only interesting to thoroughly study the extinct mammals, 
which are the most abundant fossils, but to ascertain, as far as possible, what other 
animals lived at the same time, what plants flourished, and what were the physical 
conditions generally. Was it a land of mountain chains with intervening valleys 
as it is now, or was it a vast plain with the late Cretaceous mountains worn nearly 
down to the sea level? Was the climate dry and the land a dusty, windy waste, 
or was it a region of lowland forests, rich green uplands, great lakes and broad 
rivers? Was it a time of upheaval of the strata, of earthquakes, and of volcanic 
eruptions, that made streams of molten rock, charged the waters with debris, and 
made the sky gloomy with floating dust; or did each of these conditions prevail at 
some time during this long period? Was the climate mild and uniform, or were 
there cold winter storms; and was the land hidden in snow, and the waters im- 
prisoned in ice, during a part of the year? What can we learn concerning the 
strange creatures of the times, whence they came, and whither they went? Were 
the forests, if there were any, the same as those we find there now, or have they, 
with the animals, changed? Can we throw any light on the past migration of plants 
and animals? What do these few fragmentary chapters teach us with regard to the 
transmutation of animal life ? 
