Uniformitarianism known as the Doctrine of Uniformity, is the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in the past and apply everywhere in the universe. It refers to invariance in the metaphysical principles underpinning science, such as the constancy of cause and effect throughout space-time, but has been used to describe spatiotemporal invariance of physical laws. Though an unprovable postulate that cannot be verified using the scientific method, some consider that uniformitarianism should be a required first principle in scientific research. Other scientists disagree and consider that nature is not uniform though it does exhibit certain regularities. In geology, uniformitarianism has included the gradualistic concept that "the present is the key to the past" and that geological events occur at the same rate now as they have always done, though many modern geologists no longer hold to a strict gradualism.

Coined by William Whewell, it was proposed in contrast to catastrophism by British naturalists in the late 18th century, starting with the work of the geologist James Hutton in his many books including Theory of the Earth. Hutton's work was refined by scientist John Playfair and popularised by geologist Charles Lyell's Principles of Geology in 1830. Today, Earth's history is considered to have been a slow, gradual process, punctuated by occasional natural catastrophic events; the earlier conceptions had little influence on 18th-century European geological explanations for the formation of Earth. Abraham Gottlob Werner proposed Neptunism, where strata represented deposits from shrinking seas precipitated onto primordial rocks such as granite. In 1785 James Hutton proposed an opposing, self-maintaining infinite cycle based on natural history and not on the Biblical account; the solid parts of the present land appear in general, to have been composed of the productions of the sea, of other materials similar to those now found upon the shores.

Hence we find reason to conclude:1st, That the land on which we rest is not simple and original, but that it is a composition, had been formed by the operation of second causes. 2nd, That before the present land was made, there had subsisted a world composed of sea and land, in which were tides and currents, with such operations at the bottom of the sea as now take place. And, That while the present land was forming at the bottom of the ocean, the former land maintained plants and animals. Hence we are led to conclude, that the greater part of our land, if not the whole had been produced by operations natural to this globe. Hutton sought evidence to support his idea that there must have been repeated cycles, each involving deposition on the seabed, uplift with tilting and erosion, moving undersea again for further layers to be deposited. At Glen Tilt in the Cairngorm mountains he found granite penetrating metamorphic schists, in a way which indicated to him that the presumed primordial rock had been molten after the strata had formed.

He had read about angular unconformities as interpreted by Neptunists, found an unconformity at Jedburgh where layers of greywacke in the lower layers of the cliff face have been tilted vertically before being eroded to form a level plane, under horizontal layers of Old Red Sandstone. In the spring of 1788 he took a boat trip along the Berwickshire coast with John Playfair and the geologist Sir James Hall, found a dramatic unconformity showing the same sequence at Siccar Point. Playfair recalled that "the mind seemed to grow giddy by looking so far into the abyss of time", Hutton concluded a 1788 paper he presented at the Royal Society of Edinburgh rewritten as a book, with the phrase "we find no vestige of a beginning, no prospect of an end". Both Playfair and Hall wrote their own books on the theory, for decades robust debate continued between Hutton's supporters and the Neptunists. Georges Cuvier's paleontological work in the 1790s, which established the reality of extinction, explained this by local catastrophes, after which other fixed species repopulated the affected areas.

In Britain, geologists adapted this idea into "diluvial theory" which proposed repeated worldwide annihilation and creation of new fixed species adapted to a changed environment identifying the most recent catastrophe as the biblical flood. From 1830 to 1833 Charles Lyell's multi-volume Principles of Geology was published; the work's subtitle was "An attempt to explain the former changes of the Earth's surface by reference to causes now in operation". He drew his explanations from field studies conducted directly before he went to work on the founding geology text, developed Hutton's idea that the earth was shaped by slow-moving forces still in operation today, acting over a long period of time; the terms uniformitarianism for this idea, catastrophism for the opposing viewpoint, were coined by William Whewell in a review of Lyell's book. Principles of Geology was the most influential geological work in the middle of the 19th century. Geoscientists support diverse systems of Earth history, the nature of which rest on a certain mixture of views about process, control and state which are preferred.

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The Sierra Mixteca is a mountainous region located between the states of Puebla and Oaxaca in south-central Mexico, in the region known as La Mixteca. It is known as the Nudo Mixteco or Escudo Mixteco and, in Nahuatl, as Zempoaltépetl, the name of the Cerro Zempoaltépetl, its highest peak. In the Mixtec language it is called the land of clouds; the Sierra Mixteca is one of the oldest geological regions in the territory of Mexico. It stands at the convergence of the Sierra Madre Oriental, the Neo-Volcanic Axis, the Sierra Madre del Sur. During the emergence of the two Sierra Madre ranges, the Mixtec Shield underwent intense erosion and faulting, which caused changes in the upper courses of the Rivers Balsas and Papaloapan. During that geological process, which involved high levels of volcanic activity, the rivers rising in the Sierra Mixteca carved out many deep canyons, further complicating the relief of the region. One of the most important valleys created during this period is the Tehuacán Valley, located in south-east Puebla, an area of mineral springs.

The Sierra Mixteca is one of the country's poorest regions in natural resources. Its inhabitants, who number some 200,000 are predominantly indigenous belonging to the Mixtec people, who engage in subsistence agriculture; the region lacks any major population centres and communications with the rest of the country are deficient. Sierra Mixteca

Albert Stanley was an English Liberal Party Labour Party politician and Secretary of the Midland Counties Miners' Federation. In 1877 at the age of 15 he became Secretary of his local Young Liberal Association, he was an ardent follower of William Gladstone. In 1894 he was a founding member of the Midlands Liberal Federation, he was sat until his death. He declined. However, on a third occasion in 1907 he accepted and was elected at the 1907 North West Staffordshire by-election, he sat as Member of Parliament for North West Staffordshire and was described as a Liberal–Labour politician. He was opposed to the miners affiliating to the Labour Party; when in 1909 the Miners Federation of Great Britain voted to affiliate, although a lifelong Liberal, he agreed to seek re-election as a Labour Party candidate. He was returned to the House of Commons again at the December 1910 general election, died in office in 1915, aged 52. Hansard 1803–2005: contributions in Parliament by Albert Stanley