ON THE STRATA OF LINCOLN. 555 



The quarrymen in the present day do not work below 

 these beds. ' 



15. The Oolite 2 or Roe-stone bed is nearly two feet in thick- 

 ness. Newport Arch, erected nearly 1700 years ago, and 

 for its Roman origin an object of much interest to travel- 

 lers, was built of the stone from the oolite bed. It is a 

 hard oolite, and becomes harder by exposure to a humid 

 atmosphere, which may account for its durability. In 

 some parts of this stratum it is Blue-hearted. Large 

 blocks of this oolite may be seen in the main street, a 

 little above the Hospital gates, being the remains of the 

 south Roman gate, long since destroyed. The Cathedral 

 is evidently built of the stone from the silver bed — of 

 that which underlies the silver bed — and from the beds 

 now used for foundations and walls, with a portion of the 

 oolite bed. John of Gaunt's house, now a modernized 

 dwelling, and many years the residence of the late Mr. 

 Boot, seems chiefly built of this oolite. 



16. A bed of indurated clay, six inches in thickness. 



17. A bed of very hard blue stone, which divides itself into 



two beds, by a flaw passing longitudinally through the 

 middle. 



A bed of very hard indurated clay, four inches thick, 

 divides the above bed from 



18. A thin bed of hard fine sandstone, firmly united to 



19. The Grey oolite bed, which is as firmly united to 



20. The White oolite bed. These three contiguous beds form 



indeed one massive bed, nearly four feet in thickness, 

 equal in hardness to the oolite bed of which Newport 

 Arch is built. About an inch of clay intervenes between 

 this white oolite and the 



21. Lower oolite bed, which is not so hard as the beds above, 



and which lies upon a bed of yellow ochry earth, under- 

 neath which the springs begin to appear. 3 



22. 4 Ochry ferruginous-stone bed ; — the spring water near 



Monks' House flows through its fissures, and deposits 

 the ferruginous ochre as it streams along. 



23. Ferruginous gravel and sand bed, underneath which Py- 

 rites in masses occur in some parts, just as we enter the 



1 The stone-quarries are the best places for examining the strata. 

 2 The oolite will not burn into quicklime. 



3 There are no springs in the lower part of Lincoln, the water obtained 

 there by the sinking of wells, is the river water, which is filtered through 

 the sand bed. 



4 This may be seen to advantage at the north-east corner of the Monk's 

 Leas. 



