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which took place at Mortimer's Cross, of which, in the absence of the President, 

 I had the honour to have the direction. The object of it was to familiarize the 

 eye with the best types of the Upper Ludlow formation, which, rising from below 

 the Old Red Sandstone of Herefordshire, forms the top of the Silurian system. 

 Commencing our walk at the North-field quarry, in the parish of Shobdon (the 

 equivalent of the Downton Castle building stone), we visited several sections and 

 quarries along the slopes towards Croft Castle, observing the junction of the j'ellow 

 sandstone beds, with the Old Red Sandstone near Lucton, and following down 

 the strata to the limestone in Croft Castle demesne valley (the equivalent of the 

 Ayraestry and Sedgley limestone, separating the upper from the lower Ludlow 

 rocks), which we examined on each side of the valley, and again at the Whiteway 

 Head (on the prolongation of the escarpment from Aymestry and Croft Ambrey), 

 where the strata are highly inclined, and the structure well exhibited. (See the 

 beautiful wood-cut page 243 of the Silurian System). Occasion was taken to 

 explain the meaning of the strike or direction, and the dip of rocks ; the use and 

 measure of the same ; anti-clinal and syn-clinal lines of action : the formation 

 of domes, basins, valleys of elevation, and denudation ; the actual thickness of 

 strata, in relation both to the horizontal and vertical lines drawn through them ;* 

 deceptive appearances of frequent occiurence pointed out, arising from faults, 

 repeated strata, and strata rolled over. Remarks were made on the sedimentary 

 and mineral structure of rocks, the creation of organic beings, their duration and 

 extinction, and the importance of their imbedded remains in the identification of 

 contemporary deposits. Several of the most remarkable fossils were collected. 

 I need not trouble you with their well-known names. It is an advantage of our 

 field days, that they must send us to our books ; whereas, owing to the vis 

 inerticB of our nature, the persual of the very best books on the subject will not 

 necessarily send us into the field : for this reason, most strictly one of bodily 

 and mental enjoyment, such clubs as ours are worthy of all encouragement. Our 

 walk was continued over Croft Ambrey and along the escarpment of Yatton Hill, 

 which affords most extensive and instructive views of the Old Red Sandstone 

 and Silurian districts, from the Cambrian ranges of North Wales, beyond the 

 Corndon and Stiper Stones to the basaltic top of the Clee Hills, Abberley, The 

 Lickey, Malvern, Woolhope, May Hill, The Cotteswold, Forest of Dean, and South 

 Wales. A grand physical feature, hereafter alluded to, the repetition of the upper 

 Silurian rocks, exterior of the south side of the Wigmore valley of elevation, in 

 a great bow, commencing near Aymestry, and extending to the Ambrey and the 

 Palmer's Cairn, in the parish of Orleton, was pointed out. In our descent 

 to Aymestry we took the path of an old road, up which I had the honour 

 of conducting Mr. Murchison (now Sir Roderick), in his first visit to 

 Herefordshire, July, 1831, presenting in itself a continuous section from 

 the Lower Ludlow rock to the Old Red Sandstone. I had at this time very fairly 

 developed the structure of the surrounding country. My own researches in this 

 district commenced with my residence, at Aymestry, in 1827 : but I was working 



* The thickness of any stratum in relation to a horizontal line drawn through it, is— that line 

 muhiplierl by the natural sine of the angle ot inclination of stratum ; and in reference to a 

 vertical line, is— the vertical line multiplied l)y the natural co-sine of the same angle of inclina- 

 tion. 



