About Rob Grafton Expertise I can offer help up to UK degree level and have access to the national oceanographic library in Southampton. My speciality areas are marine biology ecology and physiology although I have a good understanding of chemical oceanography and physical Oceanography.
Experience I studied and am continuing my studies of M MarBiol at the university of Southampton
Organizations University of Southampton (uk)
National Oceanography Centre Southampton (uk)
JMBUK member
Expert: Rob Grafton Date: 12/4/2007 Subject: marianas trench
Question hi Rob, my grade 4 class has a question:
What caused the formation of the deep underwater trenches?
thank you,
best regards,
neil stern
grade 4 Shaughnessy Park School
Winnipeg Manitoba Canada
-20C
Answer Deep ocean trenches, such as the Marianas trench are formed by plate tectonics. The movement of one plate under another to be precise.
The scientific term is plate subduction. It happens because one tectonic plate is heavier than another and where there is a large difference is between oceanic and continental plates. The tectonic plates that are mostly land mass are much lighter than those mostly covered in water.
The movement of the plates towards each other means that one has to go up or down. The heavy oceanic plate moves down wards and the lighter continental plate goes above the oceanic plate.this creates a V shape which is what forms deep ocean trenches.
The example you have listed above, the Marianas trench exists because the light continental Eurasian plate is pushing the heavy Philippine plate underneath it. at the bottom of the V shape this creates it has been measured to be 10,924m (almost 11km or 7 miles) that's deep enough to fit the CanWest Global Place in it 98 times one on top of each other, (and the top of the tower of towers still wouldn't quite reach the surface of the sea.
