of Geological Specimens. 



443 



particularly if they contain any petrifactions, specimens of each should be 

 taken, and numbered according to their order of succession ; marking the 

 uppermost No. 1., and thence descending with Nos. 2, 3, &c., making as 

 correct an estimate as time will permit, of the thickness of the beds. None 

 of these specimens need be more than 3 in. square, and one and a half or 

 two thick. {Jig. 108.) 



Quarry 



108 



f^tgetable Soil 

 8 ft \ 



Gravel 



Cliff 



Cliff 



3A > 



Sea 



Bones T ft. 

 Plants bft. 

 Shells \0/l. 



4. If the rocks are stratified, that is, divided into beds, state whether 

 they are horizontal, inclined, or twisted. If inclined, observe pretty nearly at 

 what angle, and to what point of the compass they dip ; if twisted, a sketch, 

 however slight, is desirable. — N. B. The true dip can seldom be ascer- 

 tained without examining the beds on more sides than one. (^g. 109.) 



Horizontal Beds. 



Inclined Beds. Dip 60°. 



Twisted Beds. 



5. One kind of rock is occasionally seen to cross and cut through the 

 beds of another. In such a case, observe whether the beds are in the same 

 plane on each side of the intruding rock ; if not, mark the extent of the 

 disturbance, and also, if there be any difference in the nature of the stone 

 of which the beds are composed, at those points where they touch the 

 intruding rock. Take specimens from the junction, and make a sketch of 



it. (Jig. no.) 



Fault, or Dislocated Beds. 



110 



Fault, or Dislocated Beds. 

 Rock A cutting through other rocks. 



6, Where there are wells, get a list of the beds sunk through in digging 

 them ; specifying the thickness of each stratum in its order, from the sur- 

 face downwards. 



7. In volcanic districts, procure a list of the volcanoes now or recently 

 in action, and of those which are extinct; stating their position, their disr 

 tance from the sea or any great lake ; the extent, nature, and, if possible, 

 the age, of particular streams of lava, or the relative age of different 

 gtreams : also, whether the lava currents conform to the valleys, or are 

 seen at different heights above the present rivers ; and also if any gravel 

 beds be discoverable beneath the streams of lava. (/^. HI.) . ; 



G G 2 



