Which preposition to use with stratums

of Occurrences 105%

This peculiarity induced us to believe that we were above the stratum of iron ore which seems to underlay most of this wild region, coloring, while it does not render impure, the waters of most of these lakes and rivers.

in Occurrences 5%

The lower stratum in the south consisted mainly of the remains of the original non-Chinese population, particularly in border and southern territories which had been newly annexed from time to time.

at Occurrences 1%

I thought, however, that she was to-day nervous and somewhat pale; and as she did not return, after permitting the pilot to seek a calmer stratum at some five fathoms depth, I followed Eveena into our cabin or chamber.

below Occurrences 1%

the vegetable stratum below which is continually rolling upward?

for Occurrences 1%

The phonolite stones of the Rhine, and the Tripoli stone, contain species identical with what are now contributing to form a sedimentary deposit (and perhaps, at some future period, a bed of rock) extending in one continuous stratum for 400 measured miles.

on Occurrences 1%

Religion was the deep underlying stratum on which their whole life was built.

around Occurrences 1%

But how came these tertiary sandstones to be so very hard, while the strata around them are so soft? Ladies and gentlemen, I know no more than you.

through Occurrences 1%

The strata through which the railway is carried, appear generally to follow in this order from London: Miles.

as Occurrences 1%

"Of course I can disguise myself too," she said enthusiastically, a new zest in her work asserting itself, now that she knew her principal co-operator was probably in the same social stratum as herself.

Which preposition to use with  stratums