HANDBOOK OF FOSSILS. 71 



against the description you have written of the bed. The gravel, 

 with its accompanying bed of sand, may be traced down, by 

 scraping away the surface, for about ten feet, when you will dis- 

 cover that it rests unevenly upon the beds below, which, instead 

 of being horizontal, slope (dip} in a N.N.E. direction, making 

 an angle of about 45 with the floor of the pit ; the gravel there- 

 fore rests successively upon the upturned ends of the lower beds, 

 and, geologically speaking, is "unconformable" to them. Now as 

 these underlying rocks were of course originally deposited in an 

 horizontal position, they must have been pushed up and the upper 

 parts worn away (denuded] before the gravel was deposited on 

 them, for the accomplishment of which process an amount of 

 time must have elapsed that it would be impossible to reckon by 

 years. 



When we come to examine these lower beds, we find first a 

 stratum of stiff dark-brown clay containing fossils disposed in 

 layers : those near the outer surface have been rendered so 

 brittle by the weather, that it is necessary to make use of the pick 

 end of the hammer and dig a little way into the face of the 

 section before we come upon some which will bear removal by 

 cutting them out with a knife. Pack them in a tin with bran, 

 or, where much clay still adheres to them, wrap them in paper. 



The true top of this bed is not visible, being concealed 

 beneath a heap of earth in the comer of the pit, but we can see 

 and measure about six feet of it. 



The next bed in order is a light brownish band of sandy clay 

 that splits along its layers into thin pieces or " lamina" whence 

 we may describe it as a sandy, laminated clay. On the freshly 

 split surface of one piece we see scattered a number of small 

 darker brown fragments ; an examination with a pocket lens 

 clearly shows that these are little bits of leaves and stems, with 

 here and there a more perfect specimen. These beds must 

 have been deposited in the still waters just off the main stream of 

 a large river which brought the plants floating down to this spot, 

 where they became water-logged and sunk ; so, too, if you examine 

 the shells in the bed immediately above, you will see that they are 

 very like though not the same as those which at the present day 

 love to dwell in the mud off the estuaries of big rivers in warmer 

 parts of the globe ; hence we discover that at some far distant 

 period a big river, but one which had no connection with that 

 running close by, once flowed over this very spot. On tracing 

 the leaf-bed down, we come all at once, at about three feet from 

 its upper surface, upon a narrow band one or two inches thick of 

 a substance composed of numerous bits of sticks and stalks 



