88 FOURTH FLOOR, SOUTH CENTRAL WING 



eruptions, while the nearby cases and pedestals contain relics of the ruined 

 city of St. Pierre and the dust, stones and bread crust bombs that were 

 thrown out in a white hot or molten condition by this volcano and by the 

 Soufriere of St. Vincent. Some 30,000 people were killed by these out- 

 breaks. Important geological facts were learned from the observation 

 and subsequent study of the series of events. 



At the north end of the hall, there is the reproduction of part of a mar- 

 velously beautiful cave that was discovered early in 1910 in the mining 

 operations at the famous Copper Queen mine at Bisbee in the southeastern 

 part of Arizona. The cave was formed by the dissolving action of water 

 traversing joints in limestone, and its walls, roof and bottom were after- 

 ward coated with calcite (calc spar) incrustations, stalactites and stalag- 

 mites, some of which are dazzling white while others are colored green with 

 copper salts or pink with iron compounds. 



In the alcove across the hall from the cave, the visitor may see the 

 stump and part of the roots of a large tree from an anthracite coal mine 

 under Scranton, Pa. Millions of years ago, in the geological 

 T st period known as the Carboniferous, this tree grew upon the 



top of a thick swamp deposit of decaying vegetation which 

 ultimately became a most valuable bed of coal. The stump was left in the 

 roof of the mine when the coal was extracted for commercial and domestic 

 uses. It fell to the floor years after the gallery had been abandoned and 

 was discovered only through the chance visit of a miner. 



The cases along both sides and down the middle of the hall contain 

 geological and palseontological specimens. Palaeontology is the science of 

 the ancient life of the earth; its field is the study of the fossilized shells 

 and other hard parts and the various kinds of imprints left by the animals 

 formerly inhabiting the seas and lands, and preserved in deposits which now 

 form our stratified rocks. As normally the upper layers of a series of strata 

 are more recent than the lower, the fossils reveal the succession of life forms 

 in the earth's crust and thus are of the highest value and interest to the 

 student of historical geology. Since, however, the remains of only a small 

 proportion of the animals living at a given period are permanently preserved 

 in the marine, river, lake and subaerial deposits of that period, the geological 

 record of animal and plant forms is far from complete. Inasmuch as in- 

 vertebrate animals are far less free in their movements than the vertebrate 

 forms, they are accepted as the best determinants of the geological age of a 

 bed of rock, even when remains of both kinds are found together. Inverte- 

 brate life too appeared on the globe far earlier than vertebrate, and remains 

 of certain species are abundant in the lowest (oldest) of our stratified rocks. 



The specimens in the cases are arranged to illustrate historical geology, 



