DEPARTMENT OF GEOLOGY. 209 



The work of preparing an exhibit for the World's Columbian Expo- 

 sition was entered upon late in September. It was decided that the 

 department should, so far as the limited appropriations permitted, 

 make an exhibit illustrative of the various phenomena grouped under 

 the heads of I, Vulcauology; II, Glaciers and Glaciation, and III, 

 Caves and Cave Deposits. 



The general character of the exhibit, as planned, may be understood 

 by reference to the outline given below : 



I. Vulcanology. 



(1) Map showing distribution of active volcanoes. 



(2) Map showing areas of volcanic rocks in the United States. 



(3) Photographs and other illustrations of active and extinct volcanoes. 



(4) Diagrams and models showing shape of volcanic cones and lava flows, crater 



lakes, hot springs and geysers, natural scenery as modified by volcanic action. 



(5) Specimens showiug volcanic products; (a) Characteristic forms, as columnar, 



slaggy, pumiceous and glassy lavas, hombs, lapilli, sand, and dust, (b) Kinds 

 of lavas, both ancient and modern, (c) Kinds ejected by same volcano at 

 different periods of activity. 



(6) Contact phenomena and secondary minerals. 



(7) Economy of volcanoes and allied phenomena (Hot Springs, etc.), as shown by 



chemical products, pozzuolana, building-stone, travertines, ''onyx" mar- 

 bles, etc. 



(8) Destructive effects as shown at Pompeii, etc. 



II. Glaciers and Glaciation . 



(1) Views illustrating living glaciers, icebergs, etc. 



(2) Relief map of the United States, showing the ice sheet of the glacial epoch in 



its lobate stage. 



(3) Illustrations of glacial phenomena, as fields covered by drift bowlders; large 



stranded bowlders illustrating direction of drift and transporting power of ice 

 sheet; kames, drumlins, etc. 



(4) Specimensshowinggrooving, striation, and polishing; drift clays, sands, gravels, 



and bowlders; scratched bowlders from till. 



(5) Economy of glaciers: View of glaciated landscapes, showing how denudation 



has rendered accessible deeply buried materials; leda clays and their utiliza- 

 tion; drift bowlders for building material. 



(6) Destructive effects : Fields covered by bowlders; forests destroyed. [Shown by 



illustrations only.] 



III. Cares anil Can' Deposits. 



(1) Theoretical sketch showing method of formation by solvent action of water. 



(2) Actual plans and sections of caves. 



(3) Cave interiors. Shown by photographs and transparencies. 



(4) Cave deposits (stalactites, stalagmites, etc.). Shown by specimens. These in 



part cut and polished to show color and structural variations. 



(5) The economy of caves. Shown by blocks and slabs of cave marble (stalagmite) ; 



nitrous earths and other salts. 



(6) Cave life. Shown by bats, eyeless fish, crayfish, insects, etc. 



(7) Caves as dwellings. 



H. Mis. 114, pt. 2 14 



