W. H. HucUeston — Creechharroiv in Piirheck. 197 



II. — Creechb ARROW IN PuRBECK, — No. 2 (continued). 

 By W. H. HuDLESTON, M.A., F.E.S., F.G.S. 

 (PLATE XI.) 

 {Concluded from the April Number, p. 154.) ~ 



Varieties of the Creechbarrow Limestone. — There are considerable 

 extremes in this respect, ranging from a soft marly deposit, which 

 soils the fingers like whitening, to a hard compact rock, which takes 

 a good polish. Unquestionably the most dense and compact lime- 

 stone is that near the summit, whilst the soft marly beds are on the 

 northern slope, and especially near the 500 feet contour, where some 

 of them are earthy and contain a considerable amount of impurity, 

 so that they may at least be called marly limestones. On the other 

 hand, there are compact white limestones, whei*e nests of dog-tooth 

 spar form no inconsiderable portion of the mass. Quartz grains may 

 be noted on most of the weathered surfaces. 



The more compact and denser limestones, which prevail near the 

 summit, may be roughly divided into non-pisolitic and pisolitic 

 rocks. Thus, for instance, I have before me (Group 1) specimens 

 of a very heavy and partially calcitic rock. It is a hard whitish, 

 limestone without pisolites, but largely interspersed with buff- 

 coloured patches, not unlike some dolomites. Calcitic nests and 

 strings occur, and also strings and stars of black oxide of 

 manganese : the external surface is rough and somewhat honey- 

 combed, and full of curious impressions, some of which may have 

 had an organic origin. 



Group 2 comprises those specimens where the pisolitic character 

 is indicated, but not very obviously. A characteristic specimen may 

 be described as follows : — A large fragment of a creamy white 

 tufaceous limestone, with specks and threads of black oxide of 

 manganese in places : flattened pisolitic bodies in brownish calcite 

 are numerous, but not very distinct. There are casts of interiors of 

 a univalve shell, which is most probably Paludina. The whole 

 of this fragment has a tufaceous aspect, and is free from buff- 

 coloured patches. The external surface is rough, and in one corner 

 is full of curious shapes, which are doubtless concretionary bodies 

 developed by weathering. On further examination of these curious 

 shapes, I note indications of the concentric structure which convinces 

 me that they are pisolites developed by weathering. 



The Pisolites.^ (Group 3.) — Originally I divided these limestones 

 into four groups, but the pisolitic limestones may be taken as 

 one group. The following is the description of a specimen of this 

 class of rock. 



A creamy tufaceous limestone with some buff-coloured patches and 

 with specks and threads of manganese oxide. Sections of ordinary 

 pisolites here and there. But this specimen is remarkable for three 

 very large horseshoe sections, which certainly represent concretions 

 in brown calcite. The first specimens I obtained were incomplete 



' The accompanying Plate is intended to illustrate concretionary or pisolitic action 

 as weU as to serve tlie palasontology of the limestone. 



