J. C. Mamel-PIeydell— Geology of Dorset. 405 



slender projecting sliarp teeth, with wide intervals, and set in advance, 

 in the lower jaw : the disproportionate magnitude of the head is very 

 remarkable, but which, as Professor Owen remarks, is more com- 

 pletely adapted to combine lightness with strength than the skull of 

 any other known vertebrate or invertebrate animal. 



Inferior Oolite. — The Inferior Oolite limestones and sands, like 

 the Lias, are confined to the north and west portions of the county, 

 extending from Oborne near Sherborne, through Bradford Abbas to 

 Berwick; they undergo much dislocation between Wayford and 

 Beaminster, and repose on the Upper Lias at their southern boun- 

 dary, while the northern portion is flanked by the Fuller's Earth. 

 They have a wide extension between Beaminster and Poorstock ; 

 two successive lateral faults occasion their disappearance at Shipton 

 Gorge. They occur again at Burton Bradstock, represented by 

 ferruginous limestones containing a large per-centage of iron. Dr. 

 Wright divides these beds into three zones, characterized by three 

 prominent Ammonites : 1. Ammonites Murcliisonice ; 2. Ammonites 

 Humpliriesianus ; 3. Ammonites ParMnsoni. No. 1 is absent in 

 Doreetshire, the result of a thinning out of the bed by which No. 2 

 is brought in conjunction with the Midford Sands. This zone is well 

 represented at Chideock and Burton Bradstock, consisting of shelly, 

 iron-shot, and brown sandy Oolites : the uppermost contains Terehra- 

 tida Phillipsii ; the middle and lower, the characteristic Ammonites ; 

 also Ammonites Sotverbyi, Ammonites concavus, Lima EtJieridgii, Tere- 

 bratula perovalis, Pleurotomaria ornata, Pleurotomaria punctata, etc. 

 The ParMnsoni zone is represented at Walditch, Chideock, Burton, 

 and Sherborne by the upper and lower Trigoni a- grits ; the former 

 contains the characteristic Ammonite, as well as Ammonites Martinsii, 

 A. Truellii, Trigonia signata — the latter contains Hyhoclypus gihherulus, 

 EcMnohi-issus climicularis. 



Fuller's Earth. — The Fuller's Earth, consisting of marls and 

 clays, spread over the upper beds of the Inferior Oolite, and of a 

 calcareous deposit known as the Fuller's Earth Eock, which forms 

 the middle beds of the series, extends from Oborne to Clifton Wood, 

 where a downthrow brings up the Forest Marble, which covers it as 

 far as Halstock, where it re-appears, passing through Leigh, and 

 South Perrott, and thence to Beaminster ; it occurs again further 

 south at Hook Park and Witherston, and disappears in the neigh- 

 bourhood of Shipton Gorge ; it finally occupies a very limited area 

 north of Burton Bradstock. These beds are not very fossiliferous : 

 the most common fossils are Ostrea acuminata and BJiynchonella 

 varians. The most westerly appearance of the Fuller's Earth is in 

 the cliif at Watton Hill, near Eype, capped by an outlying summit 

 of Forest Marble ; it occurs also as the uppermost beds of Barton 

 Cliff. The Fuller's Earth rock is confined to the northern or Yale 

 portion of the county : it is extensively quarried for the lime it 

 contains, and is largely used by the agriculturists as a top-dressing. 

 The clays produce good grass, and support an excellent pasturage. 



Forest Marble. — -This representative of the Groat Oolite consists 

 of blue clays and marls, succeeded by thick layers of stone com- 



