  Surjective homological epimorphisms with stratifying kernel can be used to
construct recollements of derived module categories. These `stratifying'
recollements are derived from recollements of module categories. Can every
recollement be put in this form, up to equivalence? A negative answer will be
given after providing a characterisation of recollements equivalent to
stratifying ones. Moreover, criteria for a ring epimorphism to be `stratifying'
will be presented as well as constructions of such epimorphisms.
