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 uncorapacted 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 {Pohjpodium 
migare). 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 affinities 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 
marlv. 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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