FOSSIL FOOTPRINTS. 71 



in the impressions of their feet upon the ground they trod 

 (fig. 21), which appears to have been a moist clay or mud pecu- 

 liarly adapted to receive impressions, and which having been 

 in many places covered over with a stratum of fine sand, and 

 then abandoned by the sea, the whole have hardened into 

 stone, and being now separated, the one contains their foot- 

 prints and the other perfect casts of them ! Nor are these 

 foot-marks all that these sandstones have to tell us of their 

 day; for the ripples of the waves, and even the little 

 pits made by drops of rain as they fell, are in this 

 most marvellous manner preserved, forming objects of wonder 

 and admiration for us mortals to contemplate, and themes 

 whereon the devout mind may pour out its tribute of praise 

 to their Great Author. How evident it is that the Creator 

 designed beforehand that we should search for these hidden 

 evidences of His handiwork, or for what purpose were they 

 thus stored up and preserved ? " Seek, and ye shall find, 

 knock, and it shall be opened unto you," are the words of 

 Grod, and they apply as fully to the material wonders of His 

 works as to the mysteries of His revealed Word. 



As the strata below the new sandstone formation was called 

 the " Carboniferous " system, from its containing much 

 carbon in the form both of coal and carbonic acid, so this has 

 been called the " Saliferous " system, from the occurrence in 

 many places of strata of " rock-salt " or crystallised chloride 

 of sodium, and (where the rain finds its way down and dis- 

 solves it) of brine springs ; these (in England) exist chiefly 

 in Cheshire and Warwickshire, but in Poland and Hungary 

 they exist on a much larger scale, the rock-salt being nearly 

 a thousand feet thick. It has been said that these strata of 

 salt were formed by the evaporation of salt lakes, but it is 

 much more probable that salt is one of the natural materials 

 of the earth, and that both salt lakes and oceans have become 

 salt from dissolving out these strata wherever they have 

 come into contact. The next sediment deposited over the 

 new red sandstone is called the " Lias," a sort of lime- 

 stone mixed with clay of a blueish-grey colour, and upon 

 this lias is again deposited the various strata known as the 

 "Oolite " (Roe-stone) system, from its appearance resembling 



