  Overlap fermions are a powerful tool for investigating the chiral and
topological structure of the vacuum and the thermal states of QCD. We study
various chiral and topological aspects of the finite temperature phase
transition of N_f=2 flavours of O(a) improved Wilson fermions, using valence
overlap fermions as a probe. Particular emphasis is placed upon the analysis of
the spectral density and the localisation properties of the eigenmodes as well
as on the local structure of topological charge fluctuations in the vicinity of
the chiral phase transition. The calculations are done on 16^3x8 lattices
generated by the DIK collaboration.
