Why study Big Rivers in a collision zone?
Study of large river systems like the Tigris provides insights about the interplay of lithospheric deformation and surface processes, as plates collide and mountains are built and eroded. The Tigris River has been geomorphically active over the past 13 million years, since the uplift of the EAP. Landscape features at aerial and ﬁeld scales show that the Tigris River valley morphology varies by reach, attesting to a complex evolution of the drainage system. First and foremost, the drainage morphology in the Upper Basin is linked to the uplift of the eastern Taurus Mountains, and deformation of the Arabian foreland system during continent–continent collision. The evolution of the Upper Tigris can be reconstructed as a function of vertical movement (e.g. base-level changes, tectonic uplift, doming, downwarp, and sagging), horizontal deformation (e.g. folding, faulting, compression, and extension), and volcanism. Weathering of the landscape has involved dissolution processes and karstic er