puhlished respecting Antrim, Derry, ^c. £71 



he so often alludes) to one very similar and immense 

 stratum of Rod Marl, as mentioned above; within which 

 they are now actually imbedded, either isolated, or touching 

 or enveloping one another, or occupyino; its entire place in 

 local tracts : and I am extremely anxious, to ensjage so de- 

 hberate and careful an observer as Dr. Richard-on, in 

 comparing these suggestions with the facts within his 

 knowledge or reach, respecting ail the norih-eastern Coun- 

 ties in Ireland, as soon as n)av be, thro'igh the inediuiTi of 

 your Magazine, or any other he may prefer: — but to pro- 

 ceed : 



This thick Red Marl stratum does not appear to have 

 formed a single plane, but to form a Trough on a large 

 scale, such as I have traced in several parts of Euiiland*, 

 the central or lowest line of which is to be sought for, by 

 the dips of the superficial strata towards ilf (where such 

 strata are regular), from near the north-western corner of 

 Aiurim along ihe vale of the lower Bann River between 

 Antrim and Derry, across Lough Neagh and thence per- 

 haps along the vale of the upper Bann, and line of the 

 Newry Canal between Down and Armagh Counties, or 

 some miles to the west of this perhaps, and into the Eastern 

 Sea, in Dundalk Bay, probably ; and I think it likely for 

 reasons to be stated hereafter, that this trough declines or 

 deepens ^owarii^ the south as far as the south side of Lough 



* As between the Isle of Wijrht and the main Land (extending- V. to the 

 French Coast and W into Dorsetshire and perhaps into Devonsliire) ; up 

 the course of the Thames from its mouiii inio Wiltshire ; and of which an 

 instance is particularized in the Ea'^t and North Ridings of Yorkshire, in 

 your present volume, page 97 and 98: they are indeed so conimon and im- 

 portant a phxnomtnon in the position of theBrilish^Strata, thnt Mr. TVtUiam 

 Simth used some years ago to think, that thereby he could account for the 

 very crooked and fingered form of the endings of the strata, without ad- 

 mitting such to lie the remains of strata of wliich the other parts are denu- 

 dated and gone, as I then and since have maintained, and ?s L)r. R. has since 

 written respecting the irregular outlines of strata which I never saw. Mr. 

 Smith, when explaining himself tome and others on this subject, has often 

 taJ:en a sheet of Avritiiig paper, and folded it up as the paper or mounting 

 of a lady's Fan is done, except the folds being parallel instead of converging 

 as in the Fan, and pulling it nearly open, has, holding it inclining slightly 

 towards the South-East, said, " this is nearer to the position of the strata 

 on the south and east of England, than any one plane, and the greater part of 

 that country will be found to con-jist of nearly parallel Ridges and Troughs." 



Local bumps, humps, or elevations in the strata, and basins, swilltys, or 

 local depressions from all sides, 1 find to be aUo common, and not less im- 

 portant to be traced and investigated, than the long Troughs and Rido-es 

 above mentioned, as I hope to show, by tlie results of a part cular Survey 

 of a large district in Derbyshire, which I have in hand, for the tiuly liberal 

 Presidtnt of the Royal Society. 



f Of whicii Mr. D. takes a general notice fqiioting the Rev. G. V. Samp- 

 lon) in p. '.'7 and 31 of hi» iitat. Surv. of Antrim. 



S 4 Ncagh, 



