W. H. Hudleston — Creechharroio in Purheck. 153 



■flints; and the amount of soft and almost pulverulent material 

 which coats so many of them is a further distinction, as this 

 substance could never endure the wear and tear of the gravel- 

 making processes. Without illustration, which would necessitate 

 the employment of colour, it is by no means easy to con-vey an 

 adequate idea of the peculiarities of the big flints, when freshly dug 

 out of the beds which contain them. Their general appearance 

 leads one to suppose that they had been subject to some corrosive 

 action, and this is especially noticeable where there are any 

 indications which may have been due to organic bodies, such as 

 urchins or sponges. 



When these Creechbarrow flints have been rolled down the 

 hillside, and subjected to atmospheric action, the external coating of 

 loose silica is found to have been entirely removed, and the flint 

 itself bleached to a dirty white condition, though the casts of Pectens 

 and other fossils still retain traces of iron-discoloration. 



Fig. 3. — Part of a calcareous uodule from No. 4 pit. Nat. size. 



TJie Manganese Nodules. — There are considerable traces of black 

 oxide of manganese both in the clays and limestones of Creech- 

 barrow, but the remarkable nodules which I am about to describe 

 have only been found in the yellow sand underlying the great flint 

 bed on the eastern spur (see p. 152). Here the most beautiful 

 botryoidal masses of this black oxide, which is probably the hydrated 

 peroxide, or psilomelane, are common and of great variety in form. 

 The one figured has a length of five inches, and its specific gravity 

 ■considerably exceeds that of the manganese nodules which are 

 figured in the description of the voyage of the " Challenger." ^ In 

 other respects there is a general resemblance, the chief dilference 

 being that in our case ordinary quartzose sand functions as the 

 material caught up by the mineral instead of fine pumice and 

 volcanic fragments, etc., as in the case of those found at the bottom 

 of the Pacific. I have not seen any nodules from the Pacific where 

 the mamillee are so salient or so rough as those from the east spur of 

 Creechbarrow, which are handsomer in shape, heavier, and present 



1 Deep Sea Deposits, pi. ii. 



