J16 



REPORT — 1900. 



of the hidden folds beneath the Chalk, must remain uncertain. The 

 Eocene deposits are not shown in this section, as they happen to have 

 been denuded along the line selected. They occur only a short distance 

 away out of the line of section. . The actual evidence seen at the surface 

 close to our site will now be described. 



On the south side of the fault the strata dip northward at varying 

 angles for a distance of about two miles from the crest of the main anti- 

 cline, the lowest rocks in the district occurring in this anticline north of 

 Radipole, where the Forest Marble appears at the surface. To this 

 succeed in order the Cornbrash, Oxford Clay, Coraliian Rocks, and 

 Kiraeridge Clay, followed at XJpway (at the south border of the map, 

 fig. 2), where the slope becomes steeper, by Portland Sand, Portland Stone, 

 and Lower Purbeck Beds. The lower quarries at Upway are in Portland 



Fig. 5. — Section of Lower Purbeck Eocks, dipping at 52°. 



^'? 





■ ■>•/-■ ' ■■.■-'■'I •.-'---■•^.''jc- ^yi-.fj^-M.-n, f.'": ■->.'■•■- ,•■.■:■•-,-.--. 



^'/iOL 



^i' J^ fT' 



iC£t 



'■i^/-:/^ 







Rock, dipping north ; the higher are in Lower Purbeck, nearly horizontal, 

 for at that point the lowest part of a synclinal fold is reached and the 

 strata begin to rise again. 



Higher up the hill in quarry and road- cutting the sections are nearly 

 continuous, the dip being about S.S.W. at angles varying from 15° to 30°. 

 Signs of lateral compression are also common, this being particularly 

 well seen on the west side of the quarry nearest to the fault, where in a 

 few yards the dip changes from nearly horizontal, with small sharp folds, 

 to an angle of 15°. At the extreme north edge of this quarry the 

 Committee undertook special excavations in order to clear up the geology 

 at a point close to the fault. We followed a particular rock bed to a 

 depth of 9 feet from the surface, obtaining the subjoined section, seen 

 from the east (fig. 5). The strata laid bare belong to the ' dirt-bed ' of the 



