34 Prof. BucKLAND and Mr. De la Beche on the 



scale, the self-same phenomena, which, in more gigantic magnitude, pervade 

 the highest Alps. 



In the eastern part of our Weymouth district, we have examples of valleys 

 of elevation, on a small scale, in the three little circus-shaped valleys of 

 Moignes Down, Poxwell, and Sutton Pointz*. All these three valleys are of 

 an elongated oval shape, and so nearly resemble the interior of a Roman 

 circus, that if the basset ends of the strata were cut into benches, the central 

 area would be visible to persons seated on every part of them. 



These three small valleys of elevation are on the same straight line, running 

 east and west, parallel to the grand axis of the Weymouth district, and also 

 parallel to two great faults adjacent to them, and immediately to be described f. 

 The western extremity of the first valley touches the eastern extremity of the 

 second, and the second is separated from the third, only for a small space, by a 

 ridge of Portland stone : each of these valleys has only one small lateral outlet 

 for the discharge of its waters ; the area of the Moignes Down Circus scarcely 

 descends below the Portland stone : those of the Poxwell Circus and Sutton 

 Pointz Circus descend into the Portland sand and Kimmeridge clay. 



In the circus of Moignes Down and of Poxwell, the circumference is chiefly 

 composed of the basset edges of strata of Portland stone dipping outwards in 

 every direction ; but the circus of Sutton Pointz, which is much longer and 

 wider than the other two, is surrounded by Portland stone on three sides only, 

 the remaining north side being partially occupied by greensand and chalk, 

 in consequence of its being intersected by the great Ridgevvay fault];. 

 Although the elevation of these circus-shaped valleys must have produced 

 vast piles of fractured strata on the line of elevation, there is no accumulation 

 of such fragments, nor any perceptible quantity of gravel of any kind within 

 their area ; the clearing out of all the rubbish which must have encumbered 

 them at the time of their elevation, can only be referred to the contempo- 

 raneous or subsequent operations of very powerful denudation. 



11. Depression. 

 Elevations of strata, such as we have been tracing, can scarcely have 

 arisen without simultaneous depressions in the spaces intermediate between 



* See Plate II. fig. 2, 3, 4. f See Map, Plate I. 



\ The circus-like inclosure of the Valley of Sutton Pointz is best seen from its eastern extremity 

 at the top of Osmington Hill, at a point on the old road near the western extremity of the Poxwell 

 Circus ; the new turnpike road from Poxwell to Osmington, enters the Poxwell Circus by the 

 outlet on its north side, and crossing its shorter diameter, cuts through the Portland stone on its 

 south side, and there enters upon the Purbeck beds, reposing on the back of the Portland stone, 

 and dipping towards Upton. See Plate II. fig. 3. 



