QUESTIONS. 337 



126. What observations are made by the geologist in regard to 

 tracks, ripples, etc. ? State the case of the slab found in Pottsville. 

 What are the two grand classes of rocks ? What is the construction 

 of stratified rocks ? Why are they called aqueous rocks ? Why fos- 

 siliferous rocks ? 



127. What are metamorphic rocks ? What is the derivation of the 

 name ? What proof is mentioned that heat is the chief agent of met- 

 amorphism ? What is said of the appearance and the formation of 

 unstratified rocks ? 



128. What is the usual difference in position of the stratified and 

 the unstratified rocks ? What is said of trappean rocks ? What is a 

 stratum ? What a stratification ? What are lamina? ? What is said 

 of them as seen in shales and micaceous sandstones ? 



129. What is said of the deposition of laminae ? How is the term 

 formation used ? What are joints and master-joints ? 



130. What is said of the regularity of these divisions in the rocks? 

 What is stated about the cliffs of Cayuga Lake ? What is cleavage 

 in rocks ? 



131. What is said of the order of succession in the strata? Give 

 the comparison of Phillips. What remarkable fact is stated about 

 the chalk formation ? What is said of flexures of strata? What of 

 the circumstances under which they were produced? State the 

 comparison in regard to ice. 



132. Illustrate the mode of producing the flexures. What fact 

 bearing on this is related by Lyell? 



133. What is said of upheavals of strata accompanied by fracture? 

 What of chasms, caverns, and natural bridges ? Illustrate the man- 

 ner in which strata are brought to view by upheavals. 



134. What is true of strata found in a vertical position ? Show 

 how strata may be supposed to be horizontal when they are far from it. 



135. Explain dip and strike. Show what anticlinal and synclinal 

 lines are. 



136. Show in detail how strata may be laid down on a map when 

 they outcrop. 



137. Show how the thickness of the strata in the above case may 

 be ascertained. 



138. What is said of the extent of knowledge that can be acquired 

 by such observations as have been detailed ? 



139. Show what are conformable and unconformable strata. What 

 are faults ? 



140. What is denudation ? What is said of the extent of the re- 

 sults effected by it ? State the case illustrating denudation occurring 

 with a fault. 



HI. State the case of the great fault spoken of by Mr. Lesley. 

 P 



