Paleozoic era

Over very long periods during the Paleozoic era, the continental shelves were covered by only a few centimeters of water. This was too shallow for currents or tidal exchange to circulate the water. Evaporation increased salinities enough to cause halite and gypsum to precipitate, forming evaporites that extend over thousands of square kilometers and range in thickness from 5 to 10 km. These are referred to as platform evaporites. 

Calmels D, Gaillerdet J, Brenot A, France-Lanord C (2007) Sustained sulfide oxidation by physical erosion processes in the Mackenzie River basin climatic perspectives. Geology 35 1003-1006 Came RE, Eiler JM, Veizer J, Azmy K, Brand U, Weidman CR (2007) Coupling of surface temperatures and atmospheric CO2 concentrations during the Paleozoic era. Nature 449 198-201 Cameron EM (1982) Sulphate and sulphate reduction in early Precambrian oceans. Nature 296 145-148... 

Cambrian Geologic period that begins the Paleozoic Era 570 million years ago. Marked in its beginning by a proliferation of animals with hard, preservable parts, such as brachiopods, trilobites, and archaeocyathids. 

Ordovician Period Geologic period of the Paleozoic Era after the Cambrian Period between 500 and 435 million years ago. Major advances during this period include the bony fish and possibly land plants (during the late Ordovician). 

Paleozoic Era The period of time beginning 570 million years ago ending 245 million years ago falls between the Proterozoic and Mesozoic Eras and is divided into the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian Periods. 

Pangaea The name proposed by German meteorologist Alfred Wegener for a supercontinent that existed at the end of the Paleozoic Era and consisted of all the Earth s landmasses. 

Permian Period The last geologic time period of the Paleozoic Era, noted for the greatest mass extinction in earth history, when nearly 96% of species died out. 

Silurian Period The geological time period of the Paleozoic Era following the Ordovician, between 435 and 395 million years ago, when plants colonized the land. 

Eucaryotes evolve Metazoans appear Invertebrates appear Paleozoic era begins, ubiquitous fossils ... 

Carboniferous. The combined Mississippian and Pennsylvanian periods of the upper Paleozoic era of the geologic time scale commenced approximately 345 million years ago. 

Permian. Referring to the last period of the Paleozoic era on the geologic time sccde commenced approximately 280 million years ago. 

Budyko (1969) argues that the study of present climatic variations is particularly important since the thermal state of the Earth-atmosphere system as well as the present ice cover are in unstable equilibrium (during 90 % of the Earth s history from the beginning of the Paleozoic era our planet was free of ice, see Section 6.1). A relatively small change in temperature would lead to irreversible change (positive feedback, see previous section). 

Cambrian The oldest geologic period between 570-510 million years ago with abundant animal fossils and the first period of the Paleozoic Era (570-245 million years ago) also denotes the system of strata deposited during this period. 

Another maceral of the inertinite group is sclerotinite, which is the result of fungal remains. Sclerotinite occurs as ovoid bodies with cell structure, with reflectance covering the entire inertinite range. Sclerotinite is found mainly in coals of the Tertiary Period, particularly in the lignites, and also in bituminous coals of the Paleozoic era. Sclerotinite (Figure 4.3) is opaque, highly reflective, and, in the oval or round form, may vary in size from 20 to 300 pm (30 to 300 x 10 mm). 

Atmospheric sciences is the study of various aspects of the nature of the atmosphere, including its origin, layered structure, density, and temperature variation with height natural variations and alterations associated with anthropogenic impacts and how it is similar to or different from other atmospheres within the solar system. The present-day atmosphere is in aU likelihood quite dissimilar from the original atmosphere. The form and composition of the present-day atmosphere is believed to have developed about 400 million years ago in the late Devonian period of the Paleozoic era, when plant life developed on land. This vegetative cover allowed plants to take in carbon dioxide and release oxygen as part of the photosynthesis process. 

The Devonian Period of the Paleozoic Era lasted from 417 million years ago to 354 million years ago. It is known as the Age of Fishes and came to an end in a dramatic mass extinction. 

---