NORWOOD — GEOLOGY OF HOTHAM. 



475 



above this Marl; but, until the relative places of these rocks are 

 accurately known, I desire to speak with great reserve of the horizon 

 and affinities of the Ligniferous Marl;" and shall better employ 

 myself in discussing its appearance, so far as I have really seen and 

 studied it, in the hope that I may induce some geologist with more 

 leisure and experience to go down to Hotham and complete the 

 investigation. A small opening made this year for road-stone, in the 

 lane-side between Hotham and the Drewton turnpike, exhibits the 

 place, breadth, and character of this limestone. Its position might 

 argue it at first sight to be " Upper Lias its width is but a few yards ; 

 and structurally it is a band of sharp irregular uncompacted stones, 

 which may be divided, not naturally but for convenience of description, 

 into two kinds. Those of what I shall call the first sort are com- 

 paratively soft and marly, of a yellowish-grey colour and general 

 fresh- water aspect, interspersed throughout with fragmentary re- 

 mains of land-plants, particularly of a fern, with a frond-lobe much 

 resembling in outline that of the common Polypody {Polypodium 

 mlgare). The venation is generally distinctly preserved : the lobe has 

 a prominent mid- vein, from which alternately, on either side, branch out 

 the lateral veins, these last being twice-forked and thus divided into four 

 branches. I am indebted to Professor Phillips for pointing out, when 

 I lately read a paper on this subject before the British Association at 

 Leeds, the affi.nities of this] fern in general ; and the interesting fact 

 which I had omitted to notice, that one specimen in my collection 

 shows its fructification. It may probably appear that the occurrence 

 of this fern is among the first indications in the Yorkshire strata of 

 a series of acrogenous plants which attained to much importance after- 

 wards, and which have been long known to us in the Upper and 

 Lower Sandstone, shale, and coal" of the Geology of Yorkshire." 

 Portions of stems occur also in this marl, but perhaps less frequently 

 than leaves of plants. 



In another division of this bed, the rock becomes harder and not so 

 marly. It changes imperceptibly to a bluish-grey colour, and is a very 

 useful road-metal, having a sharp splintery fracture, and a clear ringing 

 sound under the hammer. I have adopted this conventional 

 distinction, because I have remarked as a general rule that the wood is 

 found mostly in the softer, and the fossil animals in the harder part ; 



not but that these often run together, and admit of no line of separation 



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