Once you're on Jesus Green, turn left and walk alongside the river until you reach the Jesus Green Swimming Pool. Stand outside the entrance and look at the river. Hundreds of thousands of years ago you would have been standing (or swimming!) in a large braided river that actually flowed straight across (at right angles to) the path of the current river.

You can often see swans on the Cam

A buried channel between 10 and 15 metres deep full of gravel, sand and mud runs beneath Jesus College, under Jesus Green and carries on straight past Cambridge City football ground and north towards the Histon Road allotments. The site of Cambridge City football ground used to be called Swan's Pit; a quarry that produced the sand and gravel from which much of north Cambridge is built. Remains of cold tolerant animals such as giant deer, mammoth, woolly rhino and horse were found here in deposits that have been dated to around 180,000 years ago. At Histon Road Allotments the same channel contains ancient floodplain deposits of the River Cam from 120,000 years ago. This was the last time that the earth was as warm as it is now. These brief periods of warmth occur between long Ice Ages, and are called 'interglacials'. During the last interglacial the landscape would have looked very different, with dense woodland cloaking the surrounding hills, and hippos and elephants grazing where the houses and shops are now.

So it seems that there was another course of the river Cam. It was younger than the 'great-grandfather' that flowed along Huntingdon Road, so let's call it the 'grandfather' of the Cam! But how come the 'grandfather' river seems to have changed its course and is completely different to the river we see today?

The tree-lined Jesus Green

It appears that at some time during the last Ice Age, perhaps 50,000 years ago, the River Cam was literally captured by another river, and changed course. At the time of the last interglacial (brief period of warmth) the River Cam had been a tributary of the river Great Ouse, joining it somewhere near Over on the Ouse Valley. A huge flood combined with the destruction of the valley side by intense freezing and thawing allowed the river to adopt a new course further to the east. It appears that the River Cam settled into the new course only to be diverted further to the east by another huge flood which may have happened about 14,000 years ago, which left the river in its current course flowing to the east of Ely.

Take a moment to spot the wildlife!
You can find a wealth of wildlife by the river. Along with the swans and ducks, pike and perch you can also spot kingfishers. You might be lucky enough to see more exotic species such as black swans, Egyptian geese, wood ducks and mandarin ducks which have escaped from bird collections. Shags have also been spotted by the river, and they usually live at sea!

Look up-close for wildlife...

The trees that line the path are called 'London Planes'. Although attractive, they're not native which means they're not suitable for many of our native insects. The only insects you'll see on these trees are called 'polyphagus' - which means they eat many things! Take a close look at the tree bark and see what insects you can find!

Walk across Jesus Green along the tree-lined path until you reach the main road (Victoria Avenue). Turn right and walk along the pavement - Jesus College gardens are on your right and Midsummer Common is on your left.