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Chalk is so common in Cretaceous marine beds that the Cretaceous Period was named for these deposits. The name Cretaceous was derived from Latin creta, meaning chalk. [10] Some deposits of chalk were formed after the Cretaceous. [11] The Chalk Group is a European stratigraphic unit deposited during the late Cretaceous Period.
The coccolithophores lived in the upper part of the water column. When they died, the microscopic calcium carbonate plates, which formed their shells settled downward through the ocean water and accumulated on the ocean bottom to form a thick layer of calcareous ooze, which eventually became the Chalk Group.
Ripple marks usually form in conditions with flowing water, in the lower part of the Lower Flow Regime. There are two types of ripple marks: Symmetrical ripple marks Often found on beaches, they are created by a two way current, for example the waves on a beach (swash and backwash).
a wave that travels along the boundary between the crust and mantle P: a P wave in the mantle p: a P wave ascending to the surface from the focus R: a Rayleigh wave S: an S wave in the mantle s: an S wave ascending to the surface from the focus w: the wave reflects off the bottom of the ocean No letter is used when the wave reflects off of the ...
Marine sediment, or ocean sediment, or seafloor sediment, are deposits of insoluble particles that have accumulated on the seafloor.These particles either have their origins in soil and rocks and have been transported from the land to the sea, mainly by rivers but also by dust carried by wind and by the flow of glaciers into the sea, or they are biogenic deposits from marine organisms or from ...
A hole in a 600-mile-long fault line has been discovered at the bottom of the Pacific ocean - and it could be the trigger of a magnitude-9 earthquake on the US coast. Just outside of Oregon ...
Plate tectonics is a scientific theory developed in the 1960s that explains major land form events, such as mountain building, volcanoes, earthquakes, and mid-ocean ridge systems. [26] The idea is that Earth's most outer layer, known as the lithosphere , that is made up of the crust and mantle is divided into extensive plates of rock.
The putative galloanseran bird Austinornis lentus has been found in the Austin Chalk. [2] [3] The general absence of dinosaurs is a reflection of the Austin limestone being marine in origin, primarily composed of microscopic shell fragments from floating sea organisms known as "coccolithophores" (the same organisms that contributed to the White Cliffs of Dover, on the south coast of England). [4]