The phrase "are indeed marked" is correct and usable in written English.
It can be used to emphasize that something is clearly indicated or distinguished in a particular context.
Example: "The documents are indeed marked with the necessary signatures, confirming their authenticity."
Alternatives: "are clearly indicated" or "are distinctly labeled".
Viktor Chernomyrdin's first term as prime minister from December 1992 to March 1998 was indeed marked by the reluctant realisation that printing money would not solve Russia's problems.
While some wines were indeed marked and even marred by oak, we found much less of it than we had feared.
The years leading up to the 2008 crisis were indeed marked by unsustainable borrowing, going far beyond the subprime loans many people still believe, wrongly, were at the heart of the problem.
We can't rule on "crass", but "unfeasible" is attested in the OED from 1527 to the present day, and "infeasible" (first attested 1533) is indeed marked as "now rare".
The era was indeed marked by an unbuttoning of Victorian sexual mores, by the activities of some brave if marginal feminists (such as the British campaigners for women's suffrage), by increasing female employment and by a decline in the importance of male muscular strength.
Then, we tested by quantitative methylation specific PCR (qMSP) whether RARβ2 and CRBP1 regulatory regions in the CRABP2 knock down clones were indeed marked by DNA hypermethylation.
They are, indeed, a marking system, and one that is designed to inform interested parties.
Indeed the improvement was so marked as to make it clear that, if the captains stick to their guns, we shall soon be entirely free from the evil of which not very long ago it seemed impossible to get rid".
On the contrary, they are indeed the mark of a supermum.
Results suggest that this heterogeneity is indeed very marked.
