34 CLAY-SLATE. 
But who, in the midst of conflicting statements of 
authors, will undertake to explain what is clay-slate, 
and what is not, particularly as, this is generally 
ranked amongst the primitive (non-fossiliferous) 
rocks, and with us contains indubitable proofs of 
being fossiliferous, besides being apparently in union 
with a mass of other slate containing no such de- 
monstrations? In a popular work now before me, 
(Weekly Visitor) giving a succinct statement of 
strata, primitive formations are described as being 
destitute of petrifactions ; then, the rocks so classed 
under this head are briefly described, and amongst 
them stands “ clay-slate.” It is added, “ the clay- 
slates of Switzerland are celebrated for their impres- 
sions of fishes. Mont Pilot consists of thin lamie, 
and in almost every plate is impressed a fish”! Thus, 
it would be gratuitous and presumptuous in me, to 
draw a line of demarcation between the clay-slate 
and the other kinds of slate, (supposing a natural 
distinction to exist, which I am not sure is the case) 
for, as respects a distinction founded on the occur- 
rence of fossils, the “ grey dunstone” and greywackeé 
contain no fossils, and are, it is well known, in im- 
mediate connection with patches of fossiliferous 
slate, and consequently, the hills of slate connected 
with the fossiliferous slate above named, may, for 
aught I see, be equally regarded as coeval in their 
deposition. If therefore, it were demanded of me 
to state what I regarded as clay-slate, and to draw a 
linesof demarcation between it and other kinds, I 
should say, either that the separation must be de- 
pendent on the presence or absence of organic relics, 
presuming on the possibility of making a separation 
by that means, or, that the entire mass of our slate 
not evincing the characters of mica-slate on the one 
hand, and betraying none of the characters of flinty- 
slate or of greywacké-slate on the other—in short, 
all that rock which amongst amateurs and persons 
