438 GEOLOGY OF THE SOUTH EAST OF DORSETSHIRE. 



The composition of the beds is shown on the diagrams. — 

 The upper part of the cliff contains, in the red sand, which is 

 various in hue, and very thin bedded, nodules of white pipe- 

 clay, which were evidently washed thither from a lower or 

 distant bed, during the formation of the upper beds They 

 are all water- worn, and vary in size from a pea to a nine- 

 pound shot ; the joints of the rock have passed through them 

 as constituent portions of the mass, but there is an ochreous 

 deposit of a brighter hue round their outline, as if the parti- 

 cles of iron in the depositing water, in settling, aggregated 

 round them. Such examples as these explain the formation 

 of the darker lines in sand-stone rocks. 



Respecting the lignite bed (4 in fig. 55) which occurs here 

 in connection with red sand, it may be observed, that it well 

 represents the character of all the lignite beds in the district, 

 — the enveloping substance being an unctuous indigo-colored 

 clay when moist, and drying to a brown black, — the particles 

 of wood then appearing as if they had been charred. They 

 are extremely minute, and seem to be the relics of some 

 aquatic plant or Juncus, together with the bark and seed-ves- 

 sels of a species of pine, but it is frequently impossible to 

 detect a portion sufficiently large to discover to what it actu- 

 ally belonged. A similar bed on the other side of Poole Bay, 

 not far from Bourne Mouth, I found to contain the seed-ves- 

 sels and wood of a pine. Here the masses of fallen clay and 

 sand have heaped up a considerable quantity of debris along 

 the base of the cliffs, and furze-bushes and sand occupy the 

 space intermediate between it and the entrance to Studland, 

 which is by a road that passes up another, though smaller, 

 rent in the cliff, on each side of which there are good trans- 

 verse sections of the beds of sand traversed by faults, and 

 strata-lines, and joints, on a small but very instructive scale. 

 From this rent to another, just 238 paces more to the north- 

 west, the cliffs of sand are obscured by vegetation, and are 

 defended below by a wide beach, occupied by the beginning 

 of the dunes or sand-hills, which stretch across to the entrance 

 of Poole Harbour, and on the other side of that entrance, as 

 far as Poole Head. Of these hills of blown sand, mention 

 will be made in the proper place. 



(To be continued.) 



