sentences:  The Sulm runs on top of a thick bed of its own massive quaternary deposits, and therefore the valley bed is now quite flat although (as can be deduced from the remaining terraces on its rims) it must have been steeper initially.The river therefore breached its banks easily, and used to cause frequent major flooding, until it was regulated from the 1960s onward.A unique geographic feature in the Sulm valley is the Sausal mountain range which has its own mild microclimate, supporting a significant fraction of Styria's wine-growing economy.