Human timeline and Nature timeline The Hadean Earth is thought to have had a secondary atmosphereformed through degassing of the rocks that accumulated from planetesimal impactors. According to later models, suggested by study of ancient minerals, the atmosphere in the late Hadean period consisted largely of water vapournitrogen and carbon dioxidewith smaller amounts of carbon monoxidehydrogenand sulfur compounds. The solution of carbon dioxide in water is thought to have made the seas slightly acidicgiving it a pH of about 5. After a few months, the height of these clouds would have begun to decrease but the cloud base would still have been elevated for about the next thousand years.
About 1 billion years ago Earliest evidence of multicellular organisms metazoans. CAMBRIAN Beginning about million years ago Beginning of the Cambrian Period and "radiation of species" - in part, because many organisms began to develop hard skeletal material as part of defensive and functional body plans.
Hard body parts are shells and exoskeletons were selectively preserved and therefore easier to find as fossils in Cambrian and younger sedimentary rocks. Early Evidence of Life on a Global Scale Banded-iron formations BIFs are sedimentary mineral deposits consisting of alternating beds of iron-rich minerals mostly hematite and silica-rich layers chert or quartz formed about 3.
Theory suggests BIFs are associated with the capture of oxygen released by photosynthetic processes by iron dissolved in ancient ocean water. Once nearly all the free iron was consumed in seawater, oxygen could gradually accumulate in the atmosphere, allowing an ozone layer to form.
BIF deposits are extensive in many locations, occurring as deposits, Apes formation of deserts to thousands of feet thick. During Precambrian time, BIF deposits probably extensively covered large parts of the global ocean basins.
The BIFs we see today are only remnants of what were probably every extensive deposits. BIFs are the major source of the world's iron ore and are found preserved on all major continental shield regions.
Cells are divided into two main classes: Eukaryotes include fungi, plants, animals, and some unicellular organisms. Eukaryotic cells are capable of sexual reproduction Figure Stromatolites are found in Precambrian rocks and represent some of the earliest known fossils.
Stromatolites are known from all geologic time periods and are still occurring today, with exceptional examples resembling ancient life forms still being formed today in places like Shark Bay, Australia Figure Metazoans appeared on earth in Late Precambrian time late Proterozoic Era consisting of cells in that with growth would differentiated into unique tissue or organs used for special purposes, such a locomotion, feeding, reproduction, respiration, sensing the environment, etc.
Impression is sediments tracks, trails, resting and feeding traces and rare body impressions have been found. Ediacaran fauna—one of the earliest known occurrence of multicellular animals is the, first named for the Ediacaran hills of South Australia where they were first discovered Traces of Ediacaran fauna has been found worldwide in sedimentary rocks of about to million years very late Precambrian age and consisted of frond- and tube-shaped, soft-body organisms, mostly sessile life forms sessile meaning attached to the seabed.
Many of the fossils from this time period match "families"or "classes" of organisms still found on Earth today including segmented worms, jellyfish, chordates, and other invertebrates.
Precambrian banded-iron formation from Fremont County, Wyoming Fig. Prokaryotes and Eukaryotes Fig. Stromatolites, fossils of cyanobacteria "algae" mats, occur in rocks dating back to early Precambrian time. Stomatolites of Shark Bay, Australia, are modern living examples of stromatolites that resemble fossils from the Precambrian Era.
The Paleozoic Era The Paleozoic is the era of geologic time spanning about to million years ago. Paleozoic means "ancient life" even though evidence of life extends well back in time to some of the earliest sedimentary rocks still preserved and discovered on earth.
The term "Paleozoic" also applies to rocks that formed and accumulated in that time period. Invertebrates dominate early; fish and amphibians appear in the middle Paleozoic, and reptiles appear later. Highlights of the Paleozoic Era Evolution of plant and animal life as revealed in the Paleozoic fossil record.
Cambrian Period million years: The Cambrian Period is the first geological period of the Paleozoic Era. At the beginning of the Cambrian Period the combination of tectonic forces and erosion of the landscape allowed shallow seas to gradually cover much of North America.
The seas withdrew at the end of Cambrian time, but what was left behind was a blanket of Cambrian sedimentary rocks, collectively called the Sauk Sequence see Figures and The base of the Sauk Sequence rests on an eroded surface of ancient Precambrian-age mostly metamorphic and igneous rocks on a surface called the Great Unconformity.
The Great Unconformity is exposed in many places throughout the western United States, and is particularly well known from exposures in the base sedimentary rocks of Cambrian age exposed in the Grand Canyon above the Inner Gorge; see Figure Skeletal shell remains first appear in the Cambrian Period The "Cambrian Explosion" refers to evidence in the fossil record which shows that all major phyla were established in the transition from latest Precambrian to Early Cambrian time about to million years ago Figure Apes or Angels.
Consider the high improbability that any two Earth-like planets will form and evolve to the exact and ideal conditions that develop and support carbon-based life. formation of tropical, temperate, and cold deserts, grasslands, and forests, and largely determine their locations.
Climate Affects Where Organisms Climate Graphs of Three Types of Deserts. Fig. , p. Stepped Art. There Are Three Major Types of Grasslands (1) Tropical Temperate. Abiogenesis, or informally the origin of life, is the natural process by which life arises from non-living matter, such as simple organic compounds.
The transition from non-living to living entities was not a single event, but a gradual process of increasing complexity that involved molecular self-replication, self-assembly, autocatalysis and cell membranes. How is heat distributed to different parts of the ocean?
Explain how global air circulation and ocean currents lead to the forests, grasslands, and deserts that make up the earth’s terrestrial biomes. Weather is a local short-term temperature while climate is an area’s general pattern of weather conditions. Molnar: Investigation 4 – Formation of Deserts Explain factors in the existence and location of Earth’s deserts.
Analyze atmospheric, geographic, and oceanographic data in relation to desert formation. Explain how global air circulation and ocean currents lead to the forests, grasslands, and deserts that make up the earth’s terrestrial biomes. Weather is a local short-term temperature while climate is an area’s general pattern of weather conditions.