GLOSSARY. 



Organic Remains. See Fossils. 



Orthoceratite. The remains of an extinct genus of molluscous 

 animals, called Cephalopoda. The orthoceratites are long, 

 straight, conical-chambered shells. 



Out-crop. See Crop-out. 



Outliers. Hills or ranges of rock strata, occurring at some 

 distance from the general mass of the formations to which they 

 belong. Many of these have been caused by denudation, hav- 

 ing removed parts of the strata which once connected the out- 

 liers with the mam mass of the formation. 



Oxide. A combination of oxygen with another body. The 

 term is usually limited to such combinations as do not present 

 active acid or alkaline properties. 



P. 



Palaeontology. A science which treats of fossil remains. 



Pisolite. A calcareous mineral, composed of rounded con- 

 cretions like pease. 



Pliocene. The upper or more recent tertiary strata. This 

 group of strata is divided into the older and newer pliocene 

 rocks. 



Petroleum. A liquid mineral pitch. It is common in the re- 

 gion of salt springs in the United States. 



Porphyry. A term applied to every species of unstratifled 

 rock, in which detached crystals of feldspar are diffused through 

 a compact base of other mineral composition. 



Productus. An extinct genus of fossil bivalve shells. 



Plastic Clay. One of the beds of the eocene period. The 

 plastic clay formation is mostly composed of sands with asso- 

 ciate beds of clay. 



Pudding-stone. See Conglomerate. 



Pyrites. A mineral composed of sulphur and iron. It is 

 usually of a brass yellow, brilliant, often crystallized, and fre- 

 quently mistaken for gold. 



Q. 



Quartz. A simple mineral, composed of silex. Rock crystal 

 is an example of this mineral. 



R. 



Rock. All mineral beds, whether of sand, clay, or firmly ag- 

 gregated masses, are called rocks. 



S. 



Sandstone. A rock composed of aggregated grains of sand. 

 Saurians. Animals belonging to the lizard tribe. 

 Schist. Slate. 



