RIVER TERRACES. 659 
stone near Elk River, and the basaltic sand-rock towards the head of 
the Willammet Plains. Fine specimens, probably from the same 
formation, were obtained by Mr. Elliott, of the Expedition, from the 
neighbourhood of Fraser’s River. They occur thickly together in a 
firm blue shale. 
Mineral coal is said to occur on the coast north of Oregon, and on 
Vancouver’s Island; but as I had no opportunity of visiting the 
region, and have not seen specimens, I cannot speak of its quality or 
abundance. 
Age of the Tertiary.—The fossils of Astoria have been examined 
and described for this report by Mr. T. Conrad, and the following are 
his conclusions with regard to the age of the deposits. 
“From the investigation of the fossils previously received from Mr. 
Townsend, I had arrived at the conclusion that they were of the geolo- 
gical era of the Miocene, and the specimens you sent confirm the opinion. 
I do not recognise, it is true, any recent species of the coast of California 
or elsewhere, but neither is there any shell of the Eocene period, nor 
has the group any resemblance to that of the Eocene. On the con- 
trary, the forms are decidedly approximate to those of the Miocene 
period which occur in Great Britain and the United States. Nucula 
divaricata, for instance, closely resembles NV. Codbboldie (Sowerby) of 
the English Miocene, and Lucina acutilineata can scarcely be distin- 
guished from L. contracta, (Say,) a recent species of the Atlantic coast 
and fossil in the Miocene beds of Virginia. Natica heros, a shell of 
similar range, is quite as nearly related to the N. sazea. A similar 
number of species might be obtained from some of the Miocene loca- 
lities of Maryland or Virginia, and yet no recent species be observed 
among them. In the EKocene, and also in the Miocene strata, there 
are peculiar forms which obtain in Kurope and America, and although 
the species differ, yet they are so nearly allied that this character 
alone, independent of the percentage of extinct forms, is quite a safe 
guide to the relative ages of remote fossiliferous rocks. On this 
foundation, I speak with confidence when I assign the fossils of the 
Columbia River to the era of the Miocene.” 
River Terraces and Beach Formations. 
Oregon, west of the Cascade Range, is covered with extensive tracts 
of alluvial country. Every river has its. bottom-lands, and, in general, 
