Plate tectonic convergence at a rate of about 4 mm/year between the Eurasian and African. Plates dominates the straits of Gibraltar (Argus et al., 1989). The stratigraphic evolution of the sediment drifts is therefore greatly influenced by both regional tectonics and ocean circulation (Medialdea et al., 2009; Lopes et al., 2006; Terrinha et al., 2009; Zitellini et al., 2009). Coring results from Expedition 339 showed that initial contourite formation started at about 4.5 to 4.2 Ma ago with more prominent formation of the contourite drifts taking place in the Quaternary (Expedition 339 Scientists, 2012). Today, circulation passing through the straits of Gibraltar is noticeable and identifiable by the exchange of warm and salty MOW with cool and less salty North Atlantic water flowing into the Mediterranean Sea. The MOW has a temperature of about 12°C. The sill depth of the straits of Gibraltar known as the Camarinal Sill is about 280 m. The mixing of the MOW with the North Atlantic central water forms two water masses, one at 500 -700 m depth and the other at 800 -1400 m depth (Amber and Howe, 1979; Voelker et al., 2006; Stow et al., 2011; Voelker and de Abreu, 2011). The formation of these water masses leads to the emergence of strong bottom currents that flow northwestward along the margin above the North Atlantic Deep water and under the Atlantic Inflow Water. More importantly, the merging of these strong currents and the bathymetry of the Gulf of Cadiz has led to
10. This Figure 3 vertical cross-section exhibits a profile consistent with a tectonically [(passive)(active)] coastal region.
The Bay’s salinity varies widely from season to season and from year to year, depending on the amount of fresh water flowing from its rivers. The Bay tends to be fresher in spring, when snow melts and heavy rainstorms frequently fall. During the drier months, the Bay is usually saltier. Salinity also increases with depth. Fresh water remains at the surface because it is less dense than salt water. The water on the Bay’s eastern shore tends to be saltier than the water on the western side. This is due to two factors; most fresh water enters the Bay from its northern and western tributaries, and The Coriolis Force, a phenomenon caused by the earth’s rotation, pushes flowing water in the Northern Hemisphere to the right, causing saltier water to move up the Bay veers toward the eastern shore.
The two components that were obvious to me for the Indigenous religions of North America and Africa were mythic and ritual. After reading chapters 2 and 3. I learned that the indigenous religion of North America is very spiritual. They respect nature and preform many rituals, like the sun dance that is honoring the spirit beings or the jump dance which restores balance of the earth. The Indigenous religions of Africa have ceremonies, one of them are having the boys become men. Both, Indigenous Religions of North America and Africa, believe in some type of higher god or spirit that controls the nature and the events. The similarities for the North American and African was that they both prepare or have life practices that
Rodinia started to rift around 750 to 600 million years ago and the Iapetus Ocean opening up as seen in Figure 1, the Swift Run Formation with Grenville, volcanic debris and ash material produced the Catoctin Formation that contains flood basalts supporting Shenandoah. With modern day East Africa rift and Red Sea curst stretched, this allowed flood basalts and rhyolite seep through the ocean floor and eventually made its way to the surface.
Schulz’s article is split into five sections. The first section introduces the readers to Chris Goldfinger, a paleoseismologist at Oregon State University. Goldfinger was at a seismology conference in Kashiwa, Japan when the 2011 Tohoku
The basement rocks in the western Slave carton is older than 2.8 Ga and the known oldest rocks are the genesis found along the Acasta River which is about 3.6- 4.0 Ga old, which is estimated using the zircon dating (Isachsen & Bowring, 1994; Padgham,1992). Following by 2.8 - 3.5-Ga old genesis of Point Lake and genesis under the Yellowknife Greenstone belts, which exist over 3 Ga (Isachsen & Bowring, 1994; Padgham,1992). The major rock types include granitic to tonalitic genesis, migmatitic genesis and granodiorites, which have been deformed and metamorphosed (Fyson & Helmstaedt, 1988; Isachsen & Bowring, 1994; Padgham,1992). In the eastern Slave Craton, the basement is not confined but is correlated to the Nd-Pb isotopic boundaries
The 440 million year old Georgian Bay Formation is largely composed of fossiliferous grey-black shale (L1R). It also consists grey fine-grained limestone, sandstone and green/grey siltstone interbedded with green/grey and blue/grey shales (Bond et. al. 1976). The frequency of hard rock units increases toward the top of the formation. Recurrent tropical storms across the Ordovician seas caused the formation of shady, thin limestone with wave ripples on top. Numerous fossils can be found in the siltstones and limestone including molluscs, crinoids and gastropods
Another rifting phase started in the early Jurassic around Pliensbachian or Toarcian (Chongzhi et al., 2013; Geoscience, 2014; Tindale, Newell, Keall, & Smith, 1998). Exmouth, Barrow, Dampier and Beagle Sub-basins were created until Middle Jurassic (He, 2002; Tortopoglu, 2015) and oceanic crust was laid down to form the Argo Abyssal Plain in Late Jurassic around 164-160 Ma during the Callovian to Oxfordian then followed by the Gascoyne and Cuvier Abyssal Plain in Early Cretaceous around 125 Ma (Fullerton, Sager, & Handschumacher, 1989; Müller, Mihut, & Baldwin, 1998). Passive margin was established in North West Shelf. Rifting phase of the basin transformed into sagging phase post breakup thermal subsidence when Gondwana breakup took place during Valanginian early Cretaceous around 134Ma. During the Campanian late Cretaceous, rifting along the Australian southern margin triggered the basin inversions and wrench reactivation of basin structures on NW Shelf. These movements arose the Barrow Island above sea level and formed Novara, Resolution and Exmouth Plateau Arch in Barrow, Dampier Sub-Basins and Investigator Sub-Basin (Figure 1) (Longley et al., 2002; Sinhabaedya,
The Crato Formation lithologies were most likely deposited when there was a marine transgression; which is what the Cretaceous period is renowned for (Hu et al. 2012). The build-up of laminated limestones and different lithologies in the stratigraphic column could suggest that it was a lagoon depositional environment (Martill and Frey, 1998).
However, it was not until the second half of the 20th century that three major discoveries began to suggest how this might be possible. In 1948, a survey of the floor of the Atlantic Ocean revealed a continuous ridge running largely north to south. IT was around 1,000km wide and reaching heights of 2.5km. It was composed of volcanic rocks. Similar submarine mountain ranges were later found in the Pacific Ocean extending for over 5,000km. Magnetic surveys of the ocean floor in the 1950’s showed surprisingly regular patterns of palaeomagnetic striping about the ridges. When lavas erupt on the ocean floor, magnetic domains within iron-rich minerals in the lava are aligned with the magnetic field of the earth. This is fixed as the lava cools, and unless the rocks undergo major disturbance, they continue to record the earth’s polarity at the time of their cooling. However, as the earth’s polarity reverses around every 400,000 years, bands or stripes of normal and reverse polarity rocks are mirrored on either side of the mid-ocean ridges. This suggests that new rocks are being added equally on either side.
Questions were raised when rocks were found on the surface of the Earth that had manetization the did not corralate to the location that it was found. Also, Harry Hess suggested that the continents could have drifted and still were because the sea floor was moving much like a conveyor. (Bugielski, 1999).
The fossils in the lower silty layers were most likely formed below water by normal geological processes. The sea level rose covering the organisms and the layers of silt settled above them. In the upper sandy layers the fossils could have been formed above water by a sudden catastrophic event as a result of ongoing erosive processes. The conditions in which the fossils formed were likely a result of wave action which eroded the coast line until it was unstable. When the sea level receded there was a landslide covering the
Glaciation that are widespread can be identified based on the subglacial tillite, which is a thick layer of sediments that settle down beneath glaciers or ice caps. On top of this subglacial tillite layer is deposited marine carbonate, also known as cap carbonate. Based on their paleolatitude designated by glacial sediments’ paleomagnetism, it can be determined that these deposits are from equator region. The interaction between two types of sediments, marine (like carbonate) and subgacially deposited sediments, indicate that the glaciers had approached marine coastlines.
the deepest marine trenches in the world (Rosenburg no. 6). With the interaction of the strong currents over the many reefs the topography is in a state of constant flux and development of new navigational hazards is swift (Rosenburg no. 6).
By testing sediment and recording whether it was deposited under conditions of normal polarity and then measuring successive layers, we can build a time chart. By matching different charts from different areas with similar fossils, a more global correlation can be made.