you find younger rocks in the seafloor nearer to the spreading zone.
you find younger rocks in the seafloor nearer to the spreading zone.
where do you find younger rocks in the seafloor?
nearer to the spreading zone
seafloor spreading helps explain continental drift in the theory of plate tectonics. when oceanic plates diverge, tensional stress causes fractures to occur in the lithosphere. the motivating force for seafloor spreading ridges is tectonic plate pull rather than magma pressure, although there is typically significant magma activity at spreading ridges. at a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. hydrothermal vents are common at spreading centers. older rocks will be found farther away from the spreading zone while younger rocks will be found nearer to the spreading zone. additionally spreading rates determine if the ridge is fast, intermediate, or slow. as a general rule, fast ridges have spreading (opening) rates of more than 9 cm/year. intermediate ridges have a spreading rate of 5–9 cm/year while slow spreading ridges have a rate less than 5 cm/year.
seafloor spreading
an inlier is an area of older rocks surrounded by younger rocks. inliers are typically formed by the erosion of overlying younger rocks to reveal a limited exposure of the older underlying rocks. faulting or folding may also contribute to the observed outcrop pattern. a classic example from great britain is that of the inlier of folded ordovician and silurian rocks at horton in ribblesdale in north yorkshire which are surrounded by the younger flat-lying carboniferous limestone. the location has long been visited by geology students and experts. another example from south wales is the usk inlier in monmouthshire where silurian age rocks are upfolded amidst old red sandstone rocks of devonian age.
inliers and outliers (geology)