  We show that isotopy classes of simple closed curves in any oriented surface
admit a quandle structure with operations induced by Dehn twists, the Dehn
quandle of the surface. We further show that the monodromy of a Lefschetz
fibration can be conveniently encoded as a quandle homomorphism from the knot
quandle of the base as a manifold with a codimension 2 subspace (the set of
singular values) to the Dehn quandle of the generic fibre, and discuss
prospects for construction of invariants arising naturally from this
description of the monodromy.
