72 EAMSAY AND EVANS. — OBSERVATIONS IN GEOLOGY. 



In Europe, America, and Asia there are metamorphic rocks of 

 all geological ages ranging between the Laurentian and the 

 Eocene formations. It is, therefore, important to discover or 

 surmise to what formation or set of formations any metamorphic 

 series of rocks may belong, should any data be available for that 

 purpose. In the absence of this, the observer must be content 

 to register the character of the rocks and their modes of 

 occurrence. 



More Special Observations. 



h. With regard to ordinary stratified rocks, it is important to 

 discover whether the organic remains they contain are marine, 

 estuarine, or freshwater mollusca, fishes, reptilia, &c. 



Also whether terrestrial mammalia, insects, and land plants 

 occur, and if so to what genera and species they belong ; and, if 

 possible, to collect a sufficient quantity of all kinds of fossil 

 remains to be examined and described by the best authorities on 

 the return of the voyagers. 



L In connexion with this they should endeavour to determine 

 in an}' given section, or in sections of rocks more or less apart, 

 wJiether more than one geological formation or set of formations 

 is present, as, for example, strata that lithologically or pal^eonto- 

 logically can be compared to the European or American Silurian 

 and Carboniferous rocks, or to the Liassic and Oolitic series, or 

 to the Cretaceous series, or to the Wealden, Eocene, or to the 

 Miocene strata, &c. &c. 



Should this be practicable, it is important to endeavour to show 

 in drawn sections their order of succession and superposition in 

 the manner given in ordinary geological sections, and also the 

 way in which they are affected by faults or dislocations, either 

 visible, or that may reasonably be inferred, as for example, by later 

 deposits, No. 1 in Fig. 7, seeming to dip under older strata 2, 

 in what may be called an unnatural manner without the visible 



Fig. 7. 



intervention of a fault or faults, or of partial inversion of the 

 strata by contortion of the masses as in Fig. 8. 



I, Secondary strata ; 2, Palaeozoic strata ; f^ Fault. 



Fig. 8. 



Inverted strata. 



