According to geologist Stefan Schmid, because the Western Alps underwent a metamorphic event in the Cenozoic Era while the Austroalpine peaks underwent an event in the Cretaceous Period, the two areas show distinct differences in <answer>nappe formations</answer>. Flysch deposits in the Southern Alps of Lombardy probably occurred in the Cretaceous or later.
The Western Alps and the Austroalpine peaks show distinct differences in what?
nappe formations