180 ORGANIC REMAINS. 



quantities of such .materials have been preserved for a number of 

 ages. Besides these vegetable remains, contained in the alluvial beds, 

 there are others of a more ancient date, which occur in the regular 

 strata, and 'vhich are both abundant and various. They abound most 

 in the sandstone; the ironstone, and the different kinds of shale. 



Petrified plants, or impressions of the leaves and stems of plants, 

 are very numerous in the shale that lies over the coal seams ; as is 

 the case in all coal districts. Some of these plants are ferns, others 

 are reeds ; but there is a confused mixture of a great variety of 

 vegetables; some small, others large; some with minute and delicate 

 leaves, others with broad and spreading foliage. There is a strong 

 analogy between the shale containing these impressions or petrifac- 

 tions, and the bog earth containing preserved leaves and plants. 

 In both, the vegetables are confusedly mixed, and commonly very 

 imperfect; and in separating the laminae of both, we discover new 

 specimens in every new seam or fracture that is laid open. In the 

 bogs, however, the plants are of the kinds now growing in the British 

 Isles, which is not the case with the generality of those occurring in 

 the shale. On this account, and owing to the imperfect and friable 

 state of the plants in the coal shale, it is difficult to assign them to 

 their proper genera and species. In most of the specimens, the 

 substance of the plant seems to have been changed itito a black 

 coaly matter. Some of them are impregnated with pyrites. 



Remains of plants are found in other kinds of shale, as well as 

 in that immediately over the coal. The authors discovered seeds of 

 vegetables, apparently seeds of a kind of rtshes or reeds, imbedded 

 in what they have called the second shale, near Kirkham priory. 

 These seeds are not petrified but merely preserved; being in a soft 

 and rather pliant state. Their colour is brown or rusty ; which is 

 also the colour of some imperfect remains of leaves, found along 

 with them. Some thin bivalve shells also accompanied them. 



