200 NO COAL BELOW THE OLD RED SANDSTONE. 



ed with a few of the upper deposits. But the various 

 convulsions of which I have spoken, interfered to pre- 

 vent this order; we consequently find the strata lying 

 in all imaginable positions, sometimes flat, sometimes 

 bent, sometimes inclined, and sometimes straight on 

 end or vertical. In this way they are all, even to the 

 lowest, in one place and another, presented to our 

 view. Whatever convulsions they may have under- 

 gone, however they have been twisted and contorted, 

 their relative position to each other is always the same, 

 in whatever 'part of the woHd they may he found. 



This is a most important practical fact; as an in- 

 stance, there are many kinds of sandstone : under one 

 kind coal is always found, and this is called the new 

 red sandstone; but below the coal is another, called 

 the old red sandstone. Where this last occurs, it is a 

 positive certainty that no coal exists beneath it, and 

 consequently explorations are fruitless. A person 

 unacquainted with geology, would as soon look under 

 one sandstone formation as another, and would there- 

 fore be liable to severe losses. Such losses used fre- 

 quently to occur, before geology had arrived at its 

 present advanced state. 



It is necessary to say in a few words, how these 

 various stratifications are distinguished from one ano- 

 ther, and how their relative age can be known with 

 so much certainty. 



The different geological examinations of which I 

 have spoken, show that there were not only vast alter- 

 ations on this earth's surface, before man became its 

 inhabitant; but that race upon race, millions upon 

 millions, of animated creatures, had lived and died 

 here. With the successive changes which have depo- 

 sited the various rocks, whole classes of animals and 

 plants have been swept from existence, and replaced 

 by others, differing perhaps entirely in form and struc- 

 ture. But these races, though they disappeared, were 



