Towards the end of the last ice age, as ice began to melt and raise the sea level, water infiltrated low-lying, coastal, river valleys and plains, flooding them to form whats known as a coastal plain estuary. The Humber is a great example of one of these, the diagram below illustrates its formation.
Today, the Humber is the second-largest estuary of this type in the UK and drains a catchment equivalent to 1/5 of England. Its source begins at the merging of two rivers: the Ouse and the Trent and deposits into the North Sea, about 40 miles down stream. People often ask why it is so dirty, the reason is due to the sediment held in its waters, eroded along the courses of the Ouse, the Trent and all of their tributaries. The soft rock where the rivers run erodes very easily, known as boulder clay it was formed from the sediment generated by the large ice-sheet covering much of the North of England, Scotland and Wales during the last ice-age.
Due to the tidal movements in the Humber, the estuary is classed as one of the most dangerous waterways in the world. When the sea comes in, fresh water from upstream pushes against the salty sea water. As fresh water isn't as dense as salty water, it flows over the top of it generating incredibly strong undercurrents.
How to Claim a Find
Once at GZ you will find a notice board, on the notice board there’s plenty more information about the Humber estuary, but instead of us telling you everything here, we would like you to read the notice board and take information off it and answer the questions below. Send the answers to us as well as logging your find.
i. What is the typical salt content in the estuary at Ferriby?
ii. When did the water return to the Humber after the last ice age?
iii. How long do ships have to wait if they miss high tide in the Humber?
iv. Collect a sample of Humber water in a clear bottle (waypoint 3 is a good location to reach the water) leave it over night and describe how the sediment has settled.
Good luck and have fun!
*Please be very careful when collecting your samples from the river, make sure you are aware of the tides, we have added a link at the top of the page for tide times.