Search results
Results from the WOW.Com Content Network
The map of North America with the Western Interior Seaway during the Campanian. The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, or the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses for 34 million years.
Most flows are liquefied, and many references to fluidized sediment gravity flows are in fact incorrect and actually refer to liquefied flows. [5] Debris flow or mudflow – Grains are supported by the strength and buoyancy of the matrix. Mudflows and debris flows have cohesive strength, which makes their behavior difficult to predict using the ...
It has been suggested that, as the Earth's lithospheric plates moved over the mantle plume (the Iceland plume), the plume had earlier produced the Viluy Traps to the east, then the Siberian Traps in the Permian and Triassic periods, and later going on to produce volcanic activity on the floor of the Arctic Ocean in the Jurassic and Cretaceous ...
As originally proposed in 1980 [9] by a team of scientists led by Luis Alvarez and his son Walter, it is now generally thought that the K–Pg extinction was caused by the impact of a massive asteroid 10 to 15 km (6 to 9 mi) wide, [10] [11] 66 million years ago causing the Chicxulub crater, which devastated the global environment, mainly ...
Another phase began in the Early-Middle Jurassic (about 175 Ma), when Pangaea began to rift from the Tethys Ocean in the east to the Pacific Ocean in the west. The rifting that took place between North America and Africa produced multiple failed rifts. One rift resulted in the North Atlantic Ocean. [20]
Debris flows with volumes ranging up to about 100,000 cubic meters occur frequently in mountainous regions worldwide. The largest prehistoric flows have had volumes exceeding 1 billion cubic meters (i.e., 1 cubic kilometer). As a result of their high sediment concentrations and mobility, debris flows can be very destructive.
A buoyant sediment-laden river plume can induce a secondary turbidity current on the ocean floor by the process of convective sedimentation. [24] [4] Sediment in the initially buoyant hypopycnal flow accumulates at the base of the surface flow, [25] so that the dense lower boundary become unstable. The resulting convective sedimentation leads ...
Luis (left) and his son Walter Alvarez (right) at the K-Pg Boundary in Gubbio, Italy, 1981. In 1980, a team of researchers led by Nobel prize-winning physicist Luis Alvarez, his son, geologist Walter Alvarez, and chemists Frank Asaro and Helen Vaughn Michel discovered that sedimentary layers found all over the world at the Cretaceous–Paleogene boundary contain a concentration of iridium ...