C. LAPWOKTH ON THE MOFFA.T SEMES. 259 



We are furnished in this way with a complete and convincing 

 reply to the question left unanswered by the evidence of our pre- 

 vious sections. We have now no choice but to regard the Moffat 

 Series in the glen as being arranged in an anticlinal form ; and at 

 the same time the sequence of its component beds, as displayed in 

 our typical section of the Main Cliff, is thus demonstrated to be the 

 natural order of succession. 



(d) Physical Structure of the Glen. 



We are now able to comprehend fully the physical arrangement 

 of the strata exposed within the Glen. The Moffat Series of this 

 locality, is disposed in the form of a rude arch, which is broken 

 by three longitudinal faults. In the centre of the Glen the plane 

 of the main axis of the anticlinal is approximately perpendicular, 

 and the beds are shown in their natural position. To the north- 

 ward the axis dips to the eastward, and the strata upon its western 

 side are all inverted. In the southern portion of the Glen, on the 

 other hand, the axis dips to the westward, and it is the eastern beds 

 which are overturned. 



The central or main fault runs along the crown of the anticlinal 

 from end to end. At its southern (visible) extremity it brings 

 together the very lowest beds of the locality — the Glenkiln Shales — 

 and the highest zone of the Hartfell division. As it passes to the 

 northward it cuts obliquely across the Glenkiln beds and the lowest 

 zone of the Hartfell Shales, and brings them into unnatural collo- 

 cation with the variegated beds of the inferior portion of the Birkhill 

 division. 



The eastern fault runs approximately parallel to the central dis- 

 location, letting in a long thin wedge of Upper Hartfell and Lower 

 Birkhill beds between the main fault and the convoluted Upper 

 Birkhill beds of the eastern cliff. 



The western fault is of least importance. It is about 200 yards 

 in length, attaining its maximum effect near its centre, where the 

 truncated ends of the lower zones of the Birkhill Shales are seen in 

 contact with the Barren Mudstones. 



These three dislocations are all of the puzzling class known as 

 inverted faults — the hade being towards the ujpthrow side of the 

 break. Faults of this nature are numerous everywhere in the Moffat 

 rocks ; but the geologist is exceptionally fortunate in this district in 

 the fact that the sections on the opposite sides of the break are easily 

 interpreted, owing to the unmistakable characteristics of their com- 

 ponent zones. These faults are miniature representatives of the 

 gigautic dislocations of the Alleghanies of Pennsylvania and the 

 Alpine regions of Europe. They resemble those of the latter area 

 still further in the interesting circumstance that we have some 

 examples of the well-known " fan-shaped " structure. In the Moffat 

 district this is usually due to the fact that wedges of the inferior 

 Glenkiln and Hartfell Shales have been pressed upwards, in the 

 direction of least resistance, between converging walls of the natu- 



