222 EIGHTEENTH CENTURY. FT. HI. 



as much work as the others. This was William Smith, a 

 plain English surveyor, who was so much struck with the 

 arrangement of the different formations in the hills among 

 which he travelled that he determined to try and map them 

 out so as to show exactly how the strata are placed one 

 above the other, and what counties they pass through. 



He began his work in 1790, and travelled over the whole 

 country, chiefly on foot, marking as he went all the different 

 positions of the rocks, and collecting the shells and other 

 fossils which he found in them. He had not gone on long 

 before he observed that certain fossils which appeared in the 

 lower beds disappeared when he reached those which lay 

 above them, and that others took their place ; so that in 

 this way it was possible to use the fossils to trace out the age 

 of any particular rock, just as the face of a coin helps you to 

 tell the reign in which it was cast ; and the story told by 

 the fossils agreed very well with the divisions which he had 

 worked out by the position of the rocks above each other. 

 He was even so observant that he distinguished between 

 the fossils which had their edges fresh, showing that they 

 had not been disturbed since they were buried in the earth, 

 and those which were rubbed and water-worn. The fresh 

 ones only, he said, are of use to tell the age of a rock, for 

 those which are rubbed may have been washed out of some 

 older formation by rivers. 



In this way William Smith, for pure love of science, and 

 without any hope of gain, travelled over the whole of Eng- 

 land and Wales, mapping out the rocks and noticing all 

 their peculiarities. In 1799 he published a list or tabular 

 view of the formations with their fossils, and the places 

 where they might be seen in the hills; and in 1815 he at 

 last succeeded in completing a geological map of England, 

 which has ever since formed the foundation of our British 



