76 PHILOSOPHICAL SOCIETY OF WASHINGTON. 
eulogizing his accuracy of observation, his delicacy of manipula- 
tion, his conservatism as a theorist and as a critic of new ideas; 
and alluding to his delight in teaching and his interest in, and 
affection for, the Philosophical Society. 
Mr. PowE tu spoke of his remarkable acumen and his conspicu- 
ous mental integrity. Mr. Gruon spoke of his boyhood ; Mr. Toner 
of his ability as a practitioner; and Mr. E. Farquuar of the im- 
pression of great force conveyed by his presence and conversation. 
The resolutions were unanimously adopted. 
Mr. C. E. Durron made a communication on 
THE VOLCANOES AND LAVA FIELDS OF NEW MEXICO, 
his remarks being illustrated by photographic lantern views, and 
by a map exhibiting the boundaries of the region usually termed 
the Plateau country. 
[Abstract. ] 
Beginning at the north, the boundary of the Plateau country 
runs along the southern base of the Uinta Range to the junction 
of the latter with the Wasatch ; following the eastern base of the 
Wasatch southward it strikes off towards the southwestern corner 
of Utah; thence turning due south it crosses the Colorado river, 
and gradually shifts its course to the southeastward, preserving this 
direction for nearly 400 miles and far into New Mexico; here it 
rapidly turns north northeastward, reaching into the Valley of the 
Rio Grande, and follows the western bank of that river nearly or 
quite into Southern Colorado ; here the course of the boundary is 
somewhat indeterminate, but is, in a general way, first northwest- 
ward, then northward to the place of beginning. The western and 
southern border of the Plateau province is usually sharply defined ; 
the plateaus end generally in great cliffs suddenly terminating the 
horizontal strata, and the profiles drop down upon the rough, irreg- 
ular topography of a type peculiar to the Great Basin. The 
eastern border of the Plateau province is by no means so definite ; 
the features peculiar to it pass rather by gradual transition into 
those characterizing the Rocky Mountains of Colorado. 
Among the many geological features of this wonderful region, 
the volcanic masses are not the least interesting. Volcanic action 
has prevailed there upon a grand scale, and it may be first noted 
