Amegilla dawsoni, sometimes called the Dawson's burrowing bee is a species of bee that nests by the thousands in arid claypans in Western Australia. It is a long tongued bee, of the tribe Anthophorini and genus Amegilla, the second largest genus in Anthophorini; the Dawson's burrowing bee is one of the largest Australian bee species, growing to be 23 millimetres in length and 45 millimetres in wingspan. With the exception of their faces, the bees are covered in brown fur, if male, or brown and white fur if female, they are similar in size and coloring to Australian carpenter bees. They are known solitary nesters. Though each female bee will build her own nest, they aggregate in large communities that give the appearance of colonies, their nests are dug with individual capsules created for each brood cell. Each female will only breed once in their breeding season; the males of the species are dimorphic, based on brood provisioning strategies during development. The larger males - called majors - tend to aggressively patrol emergence areas, will compete in physical fights to mate with virgin or mated females.
On the other hand, the smaller males - called minors - which make up 80% of the male population, will wait at the fringes of the emergence area and will mate only with females who are able to fly away unmated from the immediate vicinity of their natal nests. Females indicate receptiveness or lack of receptiveness to mating by emitting particular mixes of chemical signals based on whether she has mated previously; the bee feeds only on 4 genera of plants located in the deserts of Western Australia. This resource pressure has been implicated in forcing the bees to be panmictic. Amegilla dawsoni is part of the genus Amegilla in the long tongued bees. Amegilla is the second largest genus behind the genus Anthophora. Amegilla has been divided into 11 subgenera; the genus contains bees located purely in Old World, appearing throughout Europe and Asia, with one subgenus endemic to Australia. The genera Amegilla and Anthophora are monophylic, based on a series non-homoplasious traits. Additionally, Amegilla is characterized by several autapomorphies, including a gonostylus, the male phallic organ, fused to the gonocoxite, or interior region of copulation, a curved maxillary palpus with distinctive surrounding fringe.
These traits when subjected to bootstrap analysis yielded 100% cladistic support. This dark-winged bee species is among Australia's largest bees, similar in size and coloring to Xylocopa, or carpenter bee, species; the bee can get up to 45 mm in wing span. Both sexes are densely furry, with the exception of their lower facial regions, which jut outwards and tend to be bare, colored anywhere from light yellow to dark brown; the females of this bee species tend to be sized, with head widths around 6.4-7.4 mm. The males, are dimorphic, they come in the larger majors and the smaller minors. The majors and minors differ in size, with head widths ranging from 4.9 to 7.3 mm. Minor males have been defined as those with head sizes less than 6.3 mm, while major males have head sizes above 6.3 mm. Males are allometrically sized, meaning that those with larger heads have larger mandibles and broader abdomens; the largest of the males are comparable in size to the females. Sexual dimophism can be seen in the bee coloring.
The males of this species are covered in brown hair. Meanwhile, female A. dawsoni heads and thoraxes are covered in white hair. The Amegilla dawsoni is located only in Australia; the bees can be found in the arid regions on the Western half of the continent. They are widespread across this region, with the northern and southernmost extremes of their mating and nesting distributions being 700 kilometers apart; this region is known for its limited and randomly distributed rainfall, which can result in a resource deficit of flowering plants. In this case, the bee has been known to migrate north and south along its distribution to nest in better-suited environments; this bee species practices solitary nesting, though the nests are clustered close together. An active nesting colony may contain up to 10,000 burrows; the female bee builds her nest by digging straight down into clay, or other densely packed soil and dirt. She will dig to depths between 35 centimeters; the female bee will turn to dig horizontally.
In the horizontal shaft, she will dig downwards to create brood cells. The horizontal shaft is extended with each subsequent brood cell. Females will layer two brood cells on top of one another in a doublet formation; the female bee will prepare the inside of each cell by laying down a layer of wax. She fills the layered cell with pollen from four different plant genera. With this wet mixture in place, she will lay the egg on top of the cell, cap the cell with mud, she repeats this. The flight season for this bee ranges from the months of winter to early spring; the bee is univoltine – it produces only one brood per breeding season. After remaining dormant until the following winter, the brood, laid the previous year emerges and begins the flight season and mating process; the males of the species will emerge from the nests before their female counterparts. Additionally, the minor males, with head widths less than 6.3 mm, tended to emerge before the major males, with head widths greater than 6.3 mm, over the course of the entire breeding season.
Within the span of single days in the emergence period, minor males tended to surface earlier in the day than major males. This may b
Subsoil is the layer of soil under the topsoil on the surface of the ground. Like topsoil it is composed of a variable mixture of small particles such as sand, silt and/or clay, but with a much lower percentage of organic matter and humus. Below the subsoil is the substratum, which can be sediments, or aeolian deposits; as it is lacking in dark humus, subsoil is paler in color than the overlying topsoil. It may contain the deeper roots of some plants, such as trees, but a majority of plant roots lie within the topsoil. Clay-based subsoil has been the primary source of material for adobe, rammed earth and daub, other earthen construction methods for millennia. Coarse sand, the other ingredient in most of these materials, is found in subsoil. Although by no means sterile, subsoil is barren in terms of soil organisms compared to humus-rich topsoil. Håkansson, Inge. "Subsoil compaction by vehicles with high axle load—extent and crop response". Soil and Tillage Research. 29: 277–304. Doi:10.1016/0167-198790065-5.
Retrieved October 11, 2012. Adams, Fred. Moore, B. L. "Chemical Factors Affecting Root Growth in Subsoil Horizons of Coastal Plain Soils". Vol. 47 No. 1. Soil Science Society of America Journal. Pp. 99–102. Retrieved October 11, 2012. Topsoil Soil Soil horizon Subgrade
Water is a transparent, tasteless and nearly colorless chemical substance, the main constituent of Earth's streams and oceans, the fluids of most living organisms. It is vital for all known forms of life though it provides no calories or organic nutrients, its chemical formula is H2O, meaning that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. Water is the name of the liquid state of H2O at standard ambient pressure, it forms precipitation in the form of rain and aerosols in the form of fog. Clouds are formed from suspended droplets of its solid state; when finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is water vapor. Water moves continually through the water cycle of evaporation, condensation and runoff reaching the sea. Water covers 71% of the Earth's surface in seas and oceans. Small portions of water occur as groundwater, in the glaciers and the ice caps of Antarctica and Greenland, in the air as vapor and precipitation.
Water plays an important role in the world economy. 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a major source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers and canals. Large quantities of water and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a wide variety of chemical substances. Water is central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, sport fishing, diving; the word water comes from Old English wæter, from Proto-Germanic *watar, from Proto-Indo-European *wod-or, suffixed form of root *wed-. Cognate, through the Indo-European root, with Greek ύδωρ, Russian вода́, Irish uisce, Albanian ujë; the identification of water as a substance Water is a polar inorganic compound, at room temperature a tasteless and odorless liquid, nearly colorless with a hint of blue.
This simplest hydrogen chalcogenide is by far the most studied chemical compound and is described as the "universal solvent" for its ability to dissolve many substances. This allows it to be the "solvent of life", it is the only common substance to exist as a solid and gas in normal terrestrial conditions. Water is a liquid at the pressures that are most adequate for life. At a standard pressure of 1 atm, water is a liquid between 0 and 100 °C. Increasing the pressure lowers the melting point, about −5 °C at 600 atm and −22 °C at 2100 atm; this effect is relevant, for example, to ice skating, to the buried lakes of Antarctica, to the movement of glaciers. Increasing the pressure has a more dramatic effect on the boiling point, about 374 °C at 220 atm; this effect is important in, among other things, deep-sea hydrothermal vents and geysers, pressure cooking, steam engine design. At the top of Mount Everest, where the atmospheric pressure is about 0.34 atm, water boils at 68 °C. At low pressures, water cannot exist in the liquid state and passes directly from solid to gas by sublimation—a phenomenon exploited in the freeze drying of food.
At high pressures, the liquid and gas states are no longer distinguishable, a state called supercritical steam. Water differs from most liquids in that it becomes less dense as it freezes; the maximum density of water in its liquid form is 1,000 kg/m3. The density of ice is 917 kg/m3. Thus, water expands 9% in volume as it freezes, which accounts for the fact that ice floats on liquid water; the details of the exact chemical nature of liquid water are not well understood. Pure water is described as tasteless and odorless, although humans have specific sensors that can feel the presence of water in their mouths, frogs are known to be able to smell it. However, water from ordinary sources has many dissolved substances, that may give it varying tastes and odors. Humans and other animals have developed senses that enable them to evaluate the potability of water by avoiding water, too salty or putrid; the apparent color of natural bodies of water is determined more by dissolved and suspended solids, or by reflection of the sky, than by water itself.
Light in the visible electromagnetic spectrum can traverse a couple meters of pure water without significant absorption, so that it looks transparent and colorless. Thus aquatic plants and other photosynthetic organisms can live in water up to hundreds of meters deep, because sunlight can reach them. Water vapour is invisible as a gas. Through a thickness of 10 meters or more, the intrinsic color of water is visibly turquoise, as its absorption spectrum has
Clay is a finely-grained natural rock or soil material that combines one or more clay minerals with possible traces of quartz, metal oxides and organic matter. Geologic clay deposits are composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to particle size and geometry as well as water content, become hard and non–plastic upon drying or firing. Depending on the soil's content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red. Although many occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, some overlap in particle size and other physical properties; the distinction between silt and clay varies by discipline. Geologists and soil scientists consider the separation to occur at a particle size of 2 µm, sedimentologists use 4–5 μm, colloid chemists use 1 μm.
Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits. ISO 14688 grades clay particles as being smaller than 2 silt particles as being larger. Mixtures of sand and less than 40% clay are called loam. Loam is used as a building material. Clay minerals form over long periods of time as a result of the gradual chemical weathering of rocks silicate-bearing, by low concentrations of carbonic acid and other diluted solvents; these solvents acidic, migrate through the weathering rock after leaching through upper weathered layers. In addition to the weathering process, some clay minerals are formed through hydrothermal activity. There are two types of clay deposits: secondary. Primary clays remain at the site of formation. Secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Clay deposits are associated with low energy depositional environments such as large lakes and marine basins.
Depending on the academic source, there are three or four main groups of clays: kaolinite, montmorillonite-smectite and chlorite. Chlorites are not always considered to be a clay, sometimes being classified as a separate group within the phyllosilicates. There are 30 different types of "pure" clays in these categories, but most "natural" clay deposits are mixtures of these different types, along with other weathered minerals. Varve is clay with visible annual layers, which are formed by seasonal deposition of those layers and are marked by differences in erosion and organic content; this type of deposit is common in former glacial lakes. When fine sediments are delivered into the calm waters of these glacial lake basins away from the shoreline, they settle to the lake bed; the resulting seasonal layering is preserved in an distribution of clay sediment banding. Quick clay is a unique type of marine clay indigenous to the glaciated terrains of Norway, Northern Ireland, Sweden, it is a sensitive clay, prone to liquefaction, involved in several deadly landslides.
Powder X-ray diffraction can be used to identify clays. The physical and reactive chemical properties can be used to help elucidate the composition of clays. Clays exhibit plasticity. However, when dry, clay becomes firm and when fired in a kiln, permanent physical and chemical changes occur; these changes convert the clay into a ceramic material. Because of these properties, clay is used for making pottery, both utilitarian and decorative, construction products, such as bricks and floor tiles. Different types of clay, when used with different minerals and firing conditions, are used to produce earthenware and porcelain. Prehistoric humans discovered the useful properties of clay; some of the earliest pottery shards recovered are from Japan. They are associated with the Jōmon culture and deposits they were recovered from have been dated to around 14,000 BC. Clay tablets were the first known writing medium. Scribes wrote by inscribing them with cuneiform script using a blunt reed called a stylus. Purpose-made clay balls were used as sling ammunition.
Clays sintered in fire were the first form of ceramic. Bricks, cooking pots, art objects, smoking pipes, musical instruments such as the ocarina can all be shaped from clay before being fired. Clay is used in many industrial processes, such as paper making, cement production, chemical filtering; until the late 20th century, bentonite clay was used as a mold binder in the manufacture of sand castings. Clay, being impermeable to water, is used where natural seals are needed, such as in the cores of dams, or as a barrier in landfills against toxic seepage. Studies in the early 21st century have investigated clay's absorption capacities in various applications, such as the removal of heavy metals from waste water and air purification. Traditional uses of clay as medicine goes back to prehistoric times. An example is Armenian bole, used to soothe an upset stomach; some animals such as parrots and pigs ingest clay for similar reasons. Kaolin clay and attapulgite have been used as anti-diarrheal medicines.
Clay as the defining ingredient of loam is one of the oldest building materials on Earth, among other
Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, the processes by which they change over time. Geology can include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon. Modern geology overlaps all other earth sciences, including hydrology and the atmospheric sciences, so is treated as one major aspect of integrated earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface, the processes that have shaped that structure, it provides tools to determine the relative and absolute ages of rocks found in a given location, to describe the histories of those rocks. By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, the Earth's past climates. Geologists use a wide variety of methods to understand the Earth's structure and evolution, including field work, rock description, geophysical techniques, chemical analysis, physical experiments, numerical modelling.
In practical terms, geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources, understanding of natural hazards, the remediation of environmental problems, providing insights into past climate change. Geology is a major academic discipline, it plays an important role in geotechnical engineering; the majority of geological data comes from research on solid Earth materials. These fall into one of two categories: rock and unlithified material; the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three major types of rock: igneous and metamorphic; the rock cycle illustrates the relationships among them. When a rock solidifies or crystallizes from melt, it is an igneous rock; this rock can be weathered and eroded redeposited and lithified into a sedimentary rock. It can be turned into a metamorphic rock by heat and pressure that change its mineral content, resulting in a characteristic fabric.
All three types may melt again, when this happens, new magma is formed, from which an igneous rock may once more solidify. To study all three types of rock, geologists evaluate the minerals; each mineral has distinct physical properties, there are many tests to determine each of them. The specimens can be tested for: Luster: Measurement of the amount of light reflected from the surface. Luster is broken into nonmetallic. Color: Minerals are grouped by their color. Diagnostic but impurities can change a mineral’s color. Streak: Performed by scratching the sample on a porcelain plate; the color of the streak can help name the mineral. Hardness: The resistance of a mineral to scratch. Breakage pattern: A mineral can either show fracture or cleavage, the former being breakage of uneven surfaces and the latter a breakage along spaced parallel planes. Specific gravity: the weight of a specific volume of a mineral. Effervescence: Involves dripping hydrochloric acid on the mineral to test for fizzing. Magnetism: Involves using a magnet to test for magnetism.
Taste: Minerals can have a distinctive taste, like halite. Smell: Minerals can have a distinctive odor. For example, sulfur smells like rotten eggs. Geologists study unlithified materials, which come from more recent deposits; these materials are superficial deposits. This study is known as Quaternary geology, after the Quaternary period of geologic history. However, unlithified material does not only include sediments. Magmas and lavas are the original unlithified source of all igneous rocks; the active flow of molten rock is studied in volcanology, igneous petrology aims to determine the history of igneous rocks from their final crystallization to their original molten source. In the 1960s, it was discovered that the Earth's lithosphere, which includes the crust and rigid uppermost portion of the upper mantle, is separated into tectonic plates that move across the plastically deforming, upper mantle, called the asthenosphere; this theory is supported by several types of observations, including seafloor spreading and the global distribution of mountain terrain and seismicity.
There is an intimate coupling between the movement of the plates on the surface and the convection of the mantle. Thus, oceanic plates and the adjoining mantle convection currents always move in the same direction – because the oceanic lithosphere is the rigid upper thermal boundary layer of the convecting mantle; this coupling between rigid plates moving on the surface of the Earth and the convecting mantle is called plate tectonics. The development of plate tectonics has provided a physical basis for many observations of the solid Earth. Long linear regions of geologic features are explained as plate boundaries. For example: Mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, are seen as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes are theorized as convergent boundaries, where one plate subducts, or moves, under another. Transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes.
Plate tectonics has provided a mechan
Soil is a mixture of organic matter, gases and organisms that together support life. Earth's body of soil, called the pedosphere, has four important functions: as a medium for plant growth as a means of water storage and purification as a modifier of Earth's atmosphere as a habitat for organismsAll of these functions, in their turn, modify the soil; the pedosphere interfaces with the lithosphere, the hydrosphere, the atmosphere, the biosphere. The term pedolith, used to refer to the soil, translates to ground stone in the sense "fundamental stone". Soil consists of a solid phase of minerals and organic matter, as well as a porous phase that holds gases and water. Accordingly, soil scientists can envisage soils as a three-state system of solids and gases. Soil is a product of several factors: the influence of climate, relief and the soil's parent materials interacting over time, it continually undergoes development by way of numerous physical and biological processes, which include weathering with associated erosion.
Given its complexity and strong internal connectedness, soil ecologists regard soil as an ecosystem. Most soils have a dry bulk density between 1.1 and 1.6 g/cm3, while the soil particle density is much higher, in the range of 2.6 to 2.7 g/cm3. Little of the soil of planet Earth is older than the Pleistocene and none is older than the Cenozoic, although fossilized soils are preserved from as far back as the Archean. Soil science has two basic branches of study: pedology. Edaphology studies the influence of soils on living things. Pedology focuses on the formation and classification of soils in their natural environment. In engineering terms, soil is included in the broader concept of regolith, which includes other loose material that lies above the bedrock, as can be found on the Moon and on other celestial objects as well. Soil is commonly referred to as earth or dirt. Soil is a major component of the Earth's ecosystem; the world's ecosystems are impacted in far-reaching ways by the processes carried out in the soil, from ozone depletion and global warming to rainforest destruction and water pollution.
With respect to Earth's carbon cycle, soil is an important carbon reservoir, it is one of the most reactive to human disturbance and climate change. As the planet warms, it has been predicted that soils will add carbon dioxide to the atmosphere due to increased biological activity at higher temperatures, a positive feedback; this prediction has, been questioned on consideration of more recent knowledge on soil carbon turnover. Soil acts as an engineering medium, a habitat for soil organisms, a recycling system for nutrients and organic wastes, a regulator of water quality, a modifier of atmospheric composition, a medium for plant growth, making it a critically important provider of ecosystem services. Since soil has a tremendous range of available niches and habitats, it contains most of the Earth's genetic diversity. A gram of soil can contain billions of organisms, belonging to thousands of species microbial and in the main still unexplored. Soil has a mean prokaryotic density of 108 organisms per gram, whereas the ocean has no more than 107 procaryotic organisms per milliliter of seawater.
Organic carbon held in soil is returned to the atmosphere through the process of respiration carried out by heterotrophic organisms, but a substantial part is retained in the soil in the form of soil organic matter. Since plant roots need oxygen, ventilation is an important characteristic of soil; this ventilation can be accomplished via networks of interconnected soil pores, which absorb and hold rainwater making it available for uptake by plants. Since plants require a nearly continuous supply of water, but most regions receive sporadic rainfall, the water-holding capacity of soils is vital for plant survival. Soils can remove impurities, kill disease agents, degrade contaminants, this latter property being called natural attenuation. Soils maintain a net absorption of oxygen and methane and undergo a net release of carbon dioxide and nitrous oxide. Soils offer plants physical support, water, temperature moderation and protection from toxins. Soils provide available nutrients to plants and animals by converting dead organic matter into various nutrient forms.
A typical soil is about 50% solids, 50% voids of which half is occupied by water and half by gas. The percent soil mineral and organic content can be treated as a constant, while the percent soil water and gas content is considered variable whereby a rise in one is balanced by a reduction in the other; the pore space allows for the infiltration and movement of air and water, both of which are critical for life existing in soil. Compaction, a common problem with soils, reduces this space, preventing air and water from reaching plant roots and soil organisms. Given sufficient time, an undifferentiated soil will evolve a soil profile which consists of two or more layers, referred to as soil horizons, that differ in one or more properties such as in their texture, density, consistency, temperature and reactivity; the horizons differ in thickness and gene
Soil science is the study of soil as a natural resource on the surface of the Earth including soil formation and mapping. Sometimes terms which refer to branches of soil science, such as pedology and edaphology, are used as if synonymous with soil science; the diversity of names associated with this discipline is related to the various associations concerned. Indeed, agronomists, geologists, physical geographers, biologists, silviculturists, sanitarians and specialists in regional planning, all contribute to further knowledge of soils and the advancement of the soil sciences. Soil scientists have raised concerns about how to preserve soil and arable land in a world with a growing population, possible future water crisis, increasing per capita food consumption, land degradation. Soil occupies the pedosphere, one of Earth's spheres that the geosciences use to organize the Earth conceptually; this is the conceptual perspective of pedology and edaphology, the two main branches of soil science. Pedology is the study of soil in its natural setting.
Edaphology is the study of soil in relation to soil-dependent uses. Both branches apply a combination of soil physics, soil chemistry, soil biology. Due to the numerous interactions between the biosphere and hydrosphere that are hosted within the pedosphere, more integrated, less soil-centric concepts are valuable. Many concepts essential to understanding soil come from individuals not identifiable as soil scientists; this highlights the interdisciplinary nature of soil concepts. Dependence on and curiosity about soil, exploring the diversity and dynamics of this resource continues to yield fresh discoveries and insights. New avenues of soil research are compelled by a need to understand soil in the context of climate change, greenhouse gases, carbon sequestration. Interest in maintaining the planet's biodiversity and in exploring past cultures has stimulated renewed interest in achieving a more refined understanding of soil. Most empirical knowledge of soil in nature comes from soil survey efforts.
Soil survey, or soil mapping, is the process of determining the soil types or other properties of the soil cover over a landscape, mapping them for others to understand and use. It relies on distinguishing the individual influences of the five classic soil forming factors; this effort draws upon geomorphology, physical geography, analysis of vegetation and land-use patterns. Primary data for the soil survey are supported by remote sensing; as of 2006, the World Reference Base for Soil Resources, via its Land & Water Development division, is the pre-eminent soil classification system. It replaces the previous FAO soil classification; the WRB borrows from modern soil classification concepts, including USDA soil taxonomy. The classification is based on soil morphology as an expression pedogenesis. A major difference with USDA soil taxonomy is that soil climate is not part of the system, except insofar as climate influences soil profile characteristics. Many other classification schemes exist, including vernacular systems.
The structure in vernacular systems are either nominal, giving unique names to soils or landscapes, or descriptive, naming soils by their characteristics such as red, fat, or sandy. Soils are distinguished by obvious characteristics, such as physical appearance and accompanying vegetation. A vernacular distinction familiar to many is classifying texture as light. Light soil content and better structure, take less effort to cultivate. Contrary to popular belief, light soils do not weigh less than heavy soils on an air dry basis nor do they have more porosity. Contemporaries Friedrich Albert Fallou, the German founder of modern soil science, Vasily Dokuchaev, the Russian founder of modern soil science, are both credited with being among the first to identify soil as a resource whose distinctness and complexity deserved to be separated conceptually from geology and crop production and treated as a whole; as a founding father of soil science Fallou has primacy in time. Fallou was working on the origins of soil before Dokuchaev was born, however Dokuchaev's work was more extensive and is considered to be the more significant to modern soil theory than Fallou's.
Soil had been considered a product of chemical transformations of rocks, a dead substrate from which plants derive nutritious elements. Soil and bedrock were in fact equated. Dokuchaev considers the soil as a natural body having its own genesis and its own history of development, a body with complex and multiform processes taking place within it; the soil is considered as different from bedrock. The latter becomes soil under the influence of a series of soil-formation factors. According to him, soil should be called the "daily" or outward horizons of rocks regardless of the type. A 1914 encyclopedic definition: "the different forms of earth on the surface of the rocks, formed by the breaking down or weathering of rocks". Serves to illustrate the historic view of soil. Dokuchaev's late 19th century soil concept developed in the 20th century to one of soil as earthy material, altered by living processes. A corollary conc