24 INVERTEBRATE PALAEONTOLOGY 



Mines, other than coal-mines, are rarely driven in fossili- 

 ferous rocks, while borings are usually so small in 

 diameter that the cores (if any are raised) cannot include 

 much fossil evidence. Unlike many metallic ores, fossils 

 do not tend to increase in abundance near the surface, so 

 that it may be assumed that the vast majority of fossils 

 are as yet not only uncollected, but inaccessible. 



The ruthless tools of denudation, which may carve out 

 fossils from their matrix, are not content with that 

 beneficent work ; they will not rest until the organic 

 remains, as well as the rock containing them, are 

 shattered or dissolved. Much of this destruction is 

 carried out beneath the mantle of drift, so that fossil 

 evidence is destroyed just when its appearance seemed 

 imminent. Weather beats continually against exposed 

 rock-surfaces; blows from geological hammers are few 

 and intermittent. For one fossil that is found 

 " weathered-out," scores have been weathered away. 

 These are disasters beyond human control ; but the case 

 is scarcely better when artificial processes excavate the 

 rocks. The average quarryman or miner usually picks 

 out, and possibly cherishes, large or otherwise striking 

 specimens ; but he has neither the time nor training to 

 search for less obvious fossils, nor, usually, to keep suffi- 

 cient record of the horizons from which his picked 

 samples have come. Most quarried material is trans- 

 ferred direct to lime-kilns or stone-crushers, and its 

 included fossils are as lost to Palaeontology as if they 

 had never existed. Only those specimens that happen 

 to be exposed on the occasions of rare and hurried visits 

 by " fossil-hunters " are likely to be saved ; much of the 

 evidence that these can supply may be lost if the 

 collectors are among the uninitiated. An attempt is 

 made in Chapter III. to indicate the methods to be 

 employed in collecting fossils so that their full value can 



