from alternating layers of ordinary sedimentary matter. I think you
have exactly put the chief difficulty in its strongest light--viz. what
would be the result of pure or nearly pure layers of very different
mineralogical composition being metamorphosed? I believe even such might
be converted into an ordinary varying mass of metamorphic schists. I am
certain of the correctness of my account of patches of chlorite schists
enclosed in other schist, and of enormous quartzose veins of segregation
being absolutely continuous and contemporaneous with the folia of
quartz, and such, I think, might be the result of the folia crossing
a true stratum of quartz. I think my description of the wonderful and
beautiful laminated volcanic rocks at Ascension would be worth your
looking at. (540/3. "Geological Observations on S. America," pages 166,
167; also "Geological Observations on the Volcanic Islands," Chapter
III. (Ascension), 1844.)

LETTER 541. TO C. LYELL. Down, January 14th [1855].

We were yesterday and the day before house-hunting, so I could not
answer your letter. I hope we have succeeded in a house, after infinite
trouble, but am not sure, in York Place, Baker Street.

I do not doubt that I either read or heard from Sharpe about the
Grampians; otherwise from my own old suspicion I should not have
inserted the passage in the manual.

The laminated rocks at Ascension are described at page 54. (541/1.
"Volcanic Islands," page 54. "Singular laminated beds alternating with
and passing into obsidian.")

As far as my experience has gone, I should speak only of clay-slate
being associated with mica-slate, for when near the metamorphic schists
I have found stratification so gone that I should not dare to speak of
them as overlying them. With respect to the difficulty of beds of quartz
and marble, this has for years startled me, and I have longed (since I
have felt its force) to have some opportunity of testing this point,
for without you are sure that the beds of quartz dip, as well as strike,
parallel to the foliation, the case is only just like true strata of
sandstone included in clay-slate and striking parallel to the cleavage
of the clay-slate, but of course with different dip (excepting in those
rare cases when cleavage and stratification are parallel). Having this
difficulty before my eyes, I was much struck with MacCulloch's statement
(page 166 of my "S. America") about marble in the metamorphic series not
forming