What is the "Graveyard School of Poetry"?

The 'Graveyard School' refers to a genre evolving in the domain of 18th century English poetry.Perhaps the earliest example would be Thomas Parnell's 'A Night-Piece on Death'(1721). The so-called school of poetry dealing with death, bereavement, the grave, the physical manifestations of morbidity etc was chiefly modelled on Robert Blair's long popular poem, 'The Grave'(1743). Edward Young's blank-verse poem, 'Night Thoughts'(1742-45) was a more celebrated example. Thomas Gray's famous work, 'An Elegy Written on a Country Church-Yard' reflected the more meditative aspect of this pre-Romantic school.