2O The Founders of Geology LECT. 



chemical and other symbols, he placed a sign at each 

 locality where a particular mineral substance was known 

 to exist. Moreover, employing a variety of engraved 

 shading, he showed in a general way the position and 

 limits of the great Paris basin. The marly band surround- 

 ing the central tract of sandy Tertiary strata was represented 

 as sweeping inland from the coast between Boulogne and 

 Dieppe, through Picardy and the east of Trance to the 

 Bourbonnais, where, turning westward, it reached Poitou, 

 and then struck northward to the coast west of the mouth 

 of the Seine. Though erroneously grouping Secondary some- 

 times with Palaeozoic, sometimes with Tertiary strata, and 

 not accurately coinciding with the modern divisions of 

 the stratigraphical series, the map yet roughly expresses 

 the broad distribution of the formations. 



Having put his data on the map of France, he came to 

 see that his three bands were abruptly truncated by the 

 English Channel and Strait of Dover. Carrying out the 

 principles he had established, he conjectured that these 

 bands would be found to pass under the sea and to 

 re-emerge on the shores of England. To test the truth of 

 this hypothesis, he ransacked the French versions of two 

 once famous English books Joshua Childrey's Britannia 

 Baconica^ and Gerard Boate's Ireland's Naturall Historic? 



1 "Britannia Baconica, or the natural rarities of England, Scotland 

 and Wales, according as they are to be found in every shire, historically 

 related according to the precepts of the Lord Bacon." London, 1660. 

 A French translation was published in 1662 and 1667. 



2 "Ireland's Naturall Historic, Being a true and ample description of 

 its situation, greatness, shape and nature ; of its hills, woods, heaths, 

 bogs ; of its fruitfull parts and profitable grounds, with the severall ways 

 of manuring and improving the same ; with its heads or promontories, 

 harbours, roades and bayes ; of its springs and fountains, brookes, rivers, 



