Folds Flashcards
how many plate boundaries are there and what are they
3, convergent boundaries, divergent boundaries and transformation boundaries
what do divergent boundaries do
as plates diverge from each other they new space is filled by rising lava, over time a narrow sea will form eventually an ocean basin, separating continents
what do transform boundaries do
plates move past each other causing intense seismic activity. they link other plate movement
what do convergent boundaries do
converging plates undergo subduction with the od lithosphere being consumed and recycled, creating ocean trenches, volcanism, earthquakes, metamorphism
characteristics of oceanic - oceanic convergence
the older of the two plates will be subducted as it is denser. characterised by ocean trenches and volcanic islands e.g. japan
characteristics of oceanic - continental convergence
the oceanic plate is subducted as it is the denser plate. charactererised by ocean trenches, volcanic mountains ranges e.g. andes, and metamorphism producing intermediate magma
characteristics of continental - continental convergence
subduction cannot occur as continental plates are too thick and aren’t dense enough to be subducted causing plates to converge upwards. characterised by mountain ranges, plateaus, intrusions and metamorphism e.g. european alpes
what is the relationship between tectonics and geological structures
tectonic movement produces forces which are imparted onto rocks causing them to deform, forming structures such as joints, folds and faults
what is the relationship between stress and strain
stress is the force applied and strain is the deformation caused by stress
what are the major forms of stress
compression stress - causing converging and dominant in converging boundaries; tension - causing diverging and dominant in extensional environments; shear - stresses parallel in opposite directions causing transverse breaks
what are folds
folds are rock layers that have been bent, in response to compression.
what are anticlines
strata folded upwards to form arch shape, dip away from each other, oldest strata at core
what are synclines
strata folded downwards to form trough-shape, dip towards each other, youngest strata at core
how do folds relate to engineering
folds effect engineering as they play a large part in the strength of the ground
