LIAS CLIFFS. 67 
floating down the streams in a perpendicular position, in consequence of 
the superior specific gravity of their roots. 
Proceeding from High Whitby, the cliffs fall gradually toward the 
north, and at the same time the lias rises to the height of one hundred 
feet above the sea. It however sinks again near the harbour at Whitby, 
where a great dislocation depresses it suddenly on the north, and prevents 
its distinct re-appearance as far as Sandsend. From High Whitby to 
this dislocation, though the sandstones and shales vary much in thickness 
and colours, we may notice that the thin coal seams are always most 
decisively marked, and most alluring to the adventurer, in the neigh- 
bourhood of the fossil plants which lie above the irony dogger bed. 
These plants consist wholly of what are believed to be monocotyledoneus 
tribes, like the zamiae, or cyeadeas, and ferns of many genera. They lie 
in uneven, thin, white sandstones, alternating with black micaceous shale, 
and in ironstone, which is traversed by a white aluminous earth of the 
same nature as that previously noticed at White Nab, near Scarborough. 
A particular account of all these plants will be found in the latter part 
of this work. The dogger bed beneath them is a very singular layer of 
inconstant appearance, and varying substance. Sometimes, and indeed 
generally, it is a very irony nodular sandstone ; but in other places, and 
particularly towards Whitby, it contains small pebbles of limestone, 
blende, small red ironstone, white felspar, porphyry enclosing glassy 
quartz, scoriform greenstone, red oxide of iron, Ac. Towards the 
bottom, I have, in some places, seen it full of limestone pebbles, (lias ?) 
and under these a layer of large and small ironstone balls. 
The upper lias shale may be well examined in the cliffs and on the 
scars, at low-water. Many remarkable and characteristic fossils may be 
here collected, especially the belemnites tubularis of Young, ammonites 
Mulgravius, Ac., nucula ovum of Sowerby. 
The great dislocation before mentioned, which depresses the strata 
on the north side of Whitby, extends a considerable distance up the 
valley of the Esk. Its effects are very remarkable at the sea side. On 
K 2 
