254 W. H. HucUeston — Cveechharrow in Purheck. 



as I consider most probable, they roust pass under the Pipeclay 

 series, or in some unexplained manner abut against them. 



It should be borne in mind that the whole development of the 

 Oreechbarrow Beds is totally different to the Pipeclay series of the 

 Bagshots. The following points are among the differences as shown 

 in the Creechbarrow Beds : we have a concretionary pisolitic lime- 

 stone of fresh-water origin, an abundance of large flints and other 

 coarse detritus in intimate association with fine yellow clay and 

 sands (I am informed that no flints are found in the Pipeclay 

 beds). There is also a considerable amount of oxide of manganese, 

 especially in the mechanical sediments, and the occurrence of 

 boti-yoidal nodules of this mineral is noted in some of the sands. 

 Plant-remains and carbonaceous matter are also rare. On the other 

 hand, the Pipeclay series is remarkable for the complete absence 

 of calcareous matter, the excessive fineness of its sediments, the 

 large development of pale clays with admixture of stained or 

 ' bloodshot ' clays, and the abundance of carbonaceous mattei", 

 sometimes with plant impressions and remains. 



One point of considerable importance, which can only be brought 

 out fully with the aid of a sketch-map, consists in the fact that, 

 whereas immediately to the east of Creech Farm the Pipeclay series 

 is found almost in contact with the London Clay and so continues 

 all the way to the gap at Corfe Castle, yet to the ivest of this line, 

 in the vicinity of Creechbarrow itself, we find that a distance of 

 several hundred yards separates the Lower Tertiaries from the 

 Pipeclay, the intervening space being occupied by the Creechbarrow 

 Beds. At present I can only state the fact without offering an 

 adequate explanation. We can scarcely believe that the whole 

 Creechbarrow series has been faulted out in the area where it is 

 missing, and thus we must fall back on the theory of exceptional 

 development within a limited area if we adopt the Bagshot age of 

 this very peculiar set of beds. We know from Mr. Clement Eeid's 

 memoir that the Bagshot Beds west of a certain meridian in the 

 county develop into exceedingly coarse sediments, but there is 

 nothing of this kind in Purbeck, excepting the Creechbarrow Beds 

 themselves, which are only of limited extent. 



Let us now see how this investigation bears on my thi'ee theories 

 as to the origin of the hill itself. Practically these were: (1) 

 original peculiarity of deposit, (2) exceptional tectonic disturbance, 

 (3) protection afforded by Plateau-gravel. 



Of these three the first is nearest the mark, and the third may be 

 entirely dismissed. The whole area has, of course, been greatly 

 affected by tectonic disturbance, but it is doubtful at present whether 

 anything exceptional of this nature has contributed to the formation 

 of this peculiar feature of the landscape. 



The accompanying section will serve to show the relation of the 

 mass formed by the Creechbarrow Beds to the Lower Tertiaries 

 (London Clay and Eeading Beds) and the Chalk. One important 

 point to bear in mind is that the neck of land, consisting of Lower 

 -Tertiaries, whicli connects Creechbarrow with the Chalk, has an 



