SANDSTONE, SHALE, AND COAL. 125 



ferruginous laminae, or plates, that seem to have shivered off from the 

 blocks, or with ochrey clay, apparently resulting from the decompo- 

 sition of such laminae, or of the solid stone. In such instances, and 

 indeed throughout most of its extent, the dogger contains a consider- 

 able portion of iron; and rusty coatings often exfoliate from the stone, 

 where it is exposed to the action of the atmosphere; Ferruginous 

 plates, however, sometimes accompany the dogger, in situations 

 where they can scarcely be supposed to be exfoliations, being dis- 

 persed in seams of shale, or of schistose sandstone ; in which situa- 

 tions nodules of ironstone also occur. Thus, in a part of the cover 

 of Sandsend alum rock, the dogger comprises the following beds: 



1. Hard ferruginous sandstone; 1 foot. 



2. Schistose sandstone, containing rusty plates ; 6 inches. 



3. Solid blocks, divided by vertical fissures, containing rusty 

 plates and shale ; 3 feet, 6 inches. 



4. Shale, containing plates and nodules of ironstone; 3 feet. 



5. Another bed of blocks, with cross seams, as in No. 3; 3 feet 

 6 inches. — This bed lies immediately over the alum schist. 



As an additional illustration of the nature and connections of the 

 dogger, we subjoin a list of the whole beds covering the alum rock, 

 at Littlebeck : 



1. Arenaceous shale, containing nodules of ironstone, immedi- 

 ately under the alluvium ; 20 feet. 



2. White sandstone, containing fragments of charcoal, with 

 substances resembling roots of shrubs ,• 2 feet. 



3. Another bed of sandy shale ; 2 or 3 feet. 



4. White sandstone, with fragments of charcoal ; 1 foot. 



5. Schistose sandstone, or very sandy shale; containing ironstone, 

 partly in nodules, partly in veins or plates ; 3 feet. 



6. Coarse sandstone, being properly the first bed of the dogger ; 

 1 foot. 



2 t 



