The river Tees has its source in the Pennines at Cross Fell, in an area of mosses about 700m above sea level. It drains an area of around 700 square miles.
The landforms of the upper valley include v-shaped valleys and interlocking spurs, and many small tributaries and streams. Run-off is high because of the impermeable rocks and steep slopes.
The river Tees also has High Force, a huge waterfall reaching 29m tall. High Force formed where a layer of resistant igneous rock (known as whin sill) overlies softer rock (limestone) which erodes faster.
In the middle reaches the gradient levels out and we can find meanders and Ox bow lakes. There are many meanders around the town of Yarm.
The estuary of the River Tees is huge and home to one of the largest container ports in the UK. It is also very flat and ideal for the industry of Middlesbrough.