% 



290 COOKE : LOWER OOLITES OF SCARBOROUGH. 



within short distances, and often replacing one another at the same 

 horizon in a manner such as one finds at the present day in delta 

 and other estuarine deposits where the currents are erratic and 

 constantly changing. 



Remains of animal organisms seem to be rare, as neither the 

 quarry-men nor myself have met with any specimens; but I have 

 no doubt but that careful and systematic seeking will result in the 

 finding of some forms of brackish-water or marine life. Car- 

 bonaceous fragments of ferns, cycads, and conifers are remarkably 

 abundant in all of the sandstone beds. One of these pieces, 

 measuring 15 inches long, 5 inches wide, and 5 inches thick, was 

 well preserved, and under the microscope it exhibited in its trans- 

 verse section the curvature of a segment of a circular corona ; but 

 the majority are so much changed or badly preserved that they do 

 not present any well-defined histological structure. The ferns are 

 numerous and in a much better state of preservation. The seam of 

 lignite in bed 7 extends for about 10 feet along the quarry face, and 

 is about 2 inches in thickness ; but the plant-remains in it do not 

 offer distinctive characters sufficient for specific or even generic 

 determination. All the characters of this formation seem to point 

 to the conclusion that the beds were deposited in a delta; and 

 further investigations will probably result in the finding of other 

 remains that will assist in the more exact determination of the 

 precise character of the physical conditions that then endured. 



Overlying these estuarine deposits is the representative of the 

 Yorkshire Cornbrash, a rock which, as here developed, may be 

 divided lithologically into three parts 



a. Arenaceous shales. 



b. A yellow, ferruginous ' brashy ' limestone. 



c. A hard, compact, semi-crystalline limestone, the colour of which vanes 



from a deep blue to a light ashen-grey. 



The shales are ashen-grey in colour and somewhat sandy. The 

 lower portions are very fossiliferous, the predominant forms being 

 Rhynchonella leedii 7 Waldheimia obwata^ and W. lagenalis % which 

 form thick masses with the casts of Modiola, Myacites, Gresslya, and 

 Card turn. 



The yellow rock is variously textured, but as a rule it is very 

 coarse and ■ brashy/ and it readily 



posed 



In this respect it differs distinctly 



decompo 



impercepti 



Iron 



owes its yellowish and reddish-yellow colour. Fossils are very 

 abundant, the most common being Ostrea marshii, Ammonify 



