From A Storehouse of Knowledge

Elephant hurling is a debate tactic in which a debater will refer to a large body of evidence which supposedly supports the debater's arguments, but without demonstrating that all the evidence does indeed support the argument.

Jonathan Sarfati describes it as being

when the critic throws summary arguments about complex issues to give the impression of weighty evidence, but with an unstated presumption that a large complex of underlying ideas is true, and failing to consider opposing data, usually because they have uncritically accepted the arguments from their own side.^[1]

A common example among participants in internet arguments is to refer questioners to an entire large web-site rather than to specific pages.

Reference