Eei\ T. G. Bonney—On the Roshjn Hill Claij Pit. 407 



assuming for a moment tlie ' fault ' hypothesis, we have the results 

 represented in Fig. 5. The course of the fault (F*) is conjectural, 

 as this part of the pit is under water. Yet with all this strange 

 jumble, the Kimmeridge Clay on either side of the pit is undisturbed 

 and as nearly as possible horizontal ! 



FxG. V. (Plan op Pit Flooe.) 



Explanation.— 1. Boulder Clay. 2. Chalk. 3. Upper Greensand. 4. Gault. 5. Neocomian. 

 6. Kimmeridge Clay. The dotted lines represent those parts of the outcrop of the 

 junctions of the different beds on the pit floor, which cannot he exactly followed. The 

 interval between A B and C D is about 60 paces, and the same distance is between C D 

 and E F. F, Fault. K.F, Keversed Fault. The sections are not drawn to scale. 



Supposing, however, that the irregular occurrence of the Neoco- 

 mian beds is due to denudation before the deposition of the Gault, — 

 supposing that, owing to a north-easterly dip (which is quite compati- 

 ble with the facts), the Chalk disappeared just before reaching the 

 south-west, and the Gault widened out in the same direction, so as to 

 cap all the space from X to Y : — supposing, in a word, every possible 

 simplification (that I can conceive) introduced — still a section taken 

 across the line K L will give us the collocation represented in Fig, 6, 

 in which the direction of the arrow indicates the ' throw.' 



Fig. VI. 



I conclude, therefore, that this arrangement is so extraordinary 

 that it renders the fault theory in the highest degree improbable. 

 We are accordingly driven to consider this mass of Cretaceous rocks, 

 as either slipped from above, or dropped as a boulder of a gigantic size 



