408 RETROSPECT OF THE OOLITIC SYSTEM. CHAP. 



One of my visits to Easton and Collyweston was made with 

 Sir B/. I. Murchison in 1831. We then obtained complete sections 

 of the workings for slate, and took notes of the most frequent 

 organic remains. Among other results was a conviction in my 

 mind that both in plants and animal remains, in mineral character 

 and structural aspect, and place in the strata, this slaty and flaggy 

 series corresponded very closely with the flag and slate of Brandsby 

 in Yorkshire. 



Lately, on reviewing the notes then taken, and revisiting the 

 quarries, I have found this opinion confirmed, and at the same time 

 cannot but remark, along with a certain difference in fossils and 

 mineral aspect from ' the Stonesfield beds, the analogy of the whole 

 series in respect of the physical circumstances of their deposition. 



The sections at and near Collyweston may be thus represented 

 in general terms : 



Cornbrash much as in Oxfordshire. 



Forest marble and clays much as near Stonesfield. 



Great oolite (called 'Bubble' and 'Gale') of white, yellowish, or pinkish tints, 



like that of Ketton. 8 to 1 2 feet. 

 Sandy series (called 'Bedding- sand') with remarkable concretionary curves, or 



* Potlids/ like those of Stonesfield. 3 feet where thickest. 

 Brown hard oolite in thin beds, graduating upwards to the sand (called 



' Brood'). 4 or 5 feet. 



1 Limestone' burnt for lime; hard, compact stone. 

 Solid irregular sandstone, called Bitch.' 

 The slate beds, 2 to 3 or 4 feet ; blue in the cores. 

 Sands of yellow or brown colour (supposed to be 9 feet thick). 

 . Clay thin, but yielding water. 

 Brown ferruginous rock, supposed to be 50 feet thick ; locally ' Ironstone.' 

 Upper lias clay. 150 feet. 



Comparing this section taken in Northamptonshire with those 

 in Oxfordshire mentioned in an earlier part of the volume, great 

 analogy will appear. The Stonesfield and the Collyweston beds 

 lie between the Great oolite and the lias ; they constitute part of 

 a group of sandy strata, which in the lower or lowest parts become 

 in places highly ferruginous ; and parts are sufficiently proved in 

 Northamptonshire to belong to the Inferior oolite, probably the 

 lower part of it. Aecording to this view, the two tracts of slaty 

 rock belong to some part of the series between the Great oolite 

 (upper part) and the Inferior oolite (lower part). 



When we compare the fossils of the two tracts, the first im- 



