152 OBSERVATIONS ON THE 
The Grove Shale (Z.a) passes down into (Z%.) the Bodfari. 
Sandstone, which consists of sandy mudstone with many bands 
and thick masses of tough grey sandstone, which have resisted 
denudation better than the softer mudstones, and, therefore, 
standing out prominently all over the ground, give the impression 
that they form a larger proportion of the rocks of the area than 
they really do; just as we have already observed was the case 
with the Coniston Grits. These also are fossiliferous along 
certain bands. From the tough sandstone fossils are rarely 
obtained, except where they are calcareous, evidence of which 
is generally seen in bands of brown or gingerbread coloured 
crumbling rock, the insoluble residuum when the lime has been 
dissolved away. 
From this subdivision I have obtained the following 
species :— 
Orthis elegantula | Alveolites 
Rhynchonella nucula | Crinoid stems 
Meristella sp. 
It is clearly the equivalent of the series of sandstones which, 
on the other side of the valley, occupy all the higher ground 
between Dolhyfryd, near Denbigh, and Bryneirin, on the way to 
Nantglyn. 
The Moel Fammau Sandstones (Zc. 2.) form the summit of the 
hill, dipping steadily towards the vale on the west. They are 
but the base of the great sandstone series, known as Denbigh 
Grits, and here hardly call for separation from the overlying 
sandstones. But having regard to the constancy of the 
occurrence of coarser material at this horizon, and in view of 
the marked feature to which they give rise all along the crest of 
- the Clwydian Range from Moel Fammau to Moel-y-Parc, it 
will be convenient to consider them separately. 
In the Westmorland and Yorkshire area it will be remembered 
(see pp. 142, 147)that bands of coarse grit and highly fossiliferous 
beds of sandstone occurred just where we had evidence that the 
conditions which resulted in the deposition of the Coniston 
Flags had passed away, and those which produced the massive 
sandstones of the Coniston Grit Series were coming on, 
Encrinite (Cyathocrinus) stems are not uncommon in (£c.), 
but other fossils are rare. On Moel-y-Parc, I have found 
Orthoceras gregarium and Monograptus colonus, and on Moel 
Ganol, Monticulipora. 
This lowest sandstone has generally above it a flaggy 
stage (Zc. 1.), as may be seen near Bwlchuchaf, and in the 
quarry about a mile S.S.E. of Moel-y-Parc, near Bodfari. To 
about this horizon, also, I refer the fossiliferous flags near 
Segrwyd, about a mile S.W of Denbigh, which have been so 
well worked by Mr, Luxmoore, and also the thin bedded 
sandstones of Bryneirin. This is a very important horizon 
