Slate is a fine-grained, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock. Foliation may not correspond to the original sedimentary layering, but instead is in planes perpendicular to the direction of metamorphic compression; the foliation in slate is called "slaty cleavage". It is caused by strong compression causing fine grained clay flakes to regrow in planes perpendicular to the compression; when expertly "cut" by striking parallel to the foliation, with a specialized tool in the quarry, many slates will display a property called fissility, forming smooth flat sheets of stone which have long been used for roofing, floor tiles, other purposes. Slate is grey in color when seen, en masse, covering roofs. However, slate occurs in a variety of colors from a single locality. Slate is not to schist; the word "slate" is used for certain types of object made from slate rock.
It may mean a writing slate. They were traditionally a small, smooth piece of the rock framed in wood, used with chalk as a notepad or noticeboard, for recording charges in pubs and inns; the phrases "clean slate" and "blank slate" come from this usage. Before the mid-19th century, the terms slate and schist were not distinguished. In the context of underground coal mining in the United States, the term slate was used to refer to shale well into the 20th century. For example, roof slate referred to shale above a coal seam, draw slate referred to shale that fell from the mine roof as the coal was removed. Slate is composed of the minerals quartz and muscovite or illite along with biotite, chlorite and pyrite and, less apatite, kaolinite, tourmaline, or zircon as well as feldspar; as in the purple slates of North Wales, ferrous reduction spheres form around iron nuclei, leaving a light green spotted texture. These spheres are sometimes deformed by a subsequent applied stress field to ovoids, which appear as ellipses when viewed on a cleavage plane of the specimen.
Slate can be made into roofing slates, a type of roof shingle, or more a type of roof tile, which are installed by a slater. Slate has two lines of breakability – cleavage and grain – which make it possible to split the stone into thin sheets; when broken, slate retains a natural appearance while remaining flat and easy to stack. A "slate boom" occurred in Europe from the 1870s until the first world war, allowed by the use of the steam engine in manufacturing slate tiles and improvements in road and waterway transportation systems. Slate is suitable as a roofing material as it has an low water absorption index of less than 0.4%, making the material waterproof. In fact, this natural slate, which requires only minimal processing, has the lowest embodied energy of all roofing materials. Natural slate is used by building professionals as a result of its durability. Slate is durable and can last several hundred years with little or no maintenance, its low water absorption makes it resistant to frost damage and breakage due to freezing.
Natural slate is fire resistant and energy efficient. Slate roof tiles are fixed either with nails, or with hooks as is common with Spanish slate. In the UK, fixing is with double nails onto timber battens or nailed directly onto timber sarking boards. Nails were traditionally of copper, although there are modern alloy and stainless steel alternatives. Both these methods, if used properly, provide a long-lasting weathertight roof with a lifespan of around 80–100 years; some mainland European slate suppliers suggest that using hook fixing means that: Areas of weakness on the tile are fewer since no holes have to be drilled Roofing features such as valleys and domes are easier to create since narrow tiles can be used Hook fixing is suitable in regions subject to severe weather conditions, since there is greater resistance to wind uplift, as the lower edge of the slate is secured. The metal hooks are, however and may be unsuitable for historic properties. Slate tiles are used for interior and exterior flooring, stairs and wall cladding.
Tiles are grouted along the edges. Chemical sealants are used on tiles to improve durability and appearance, increase stain resistance, reduce efflorescence, increase or reduce surface smoothness. Tiles are sold gauged, meaning that the back surface is ground for ease of installation. Slate flooring can be slippery. Slate tiles were used in 19th century UK building construction and in slate quarrying areas such as Blaenau Ffestiniog and Bethesda, Wales there are still many buildings wholly constructed of slate. Slates can be set into walls to provide a rudimentary damp-proof membrane. Small offcuts are used as shims to level floor joists. In areas where slate is plentiful it is used in pieces of various sizes for building walls and hedges, sometimes combined with other kinds of stone. In modern homes slate is used as table coasters; because it is a good electrical insulator and fireproof, it was used to construct early-20th-century electric switchboards and relay controls for large electric motors.
Fine slate can be used as a whe
Isle of Arran
Arran or the Isle of Arran is an island off the coast of Scotland, in the United Kingdom. It is the largest island in the Firth of Clyde and the seventh largest Scottish island, at 432 square kilometres. Part of Buteshire, it is in the unitary council area of North Ayrshire. In the 2011 census it had a resident population of 4,629. Though culturally and physically similar to the Hebrides, it is separated from them by the Kintyre peninsula. Referred to as "Scotland in miniature", the island is divided into highland and lowland areas by the Highland Boundary Fault and has been described as a "geologist's paradise". Arran has been continuously inhabited since the early Neolithic period. Numerous prehistoric remains have been found. From the 6th century onwards, Goidelic-speaking peoples from Ireland colonised it and it became a centre of religious activity. In the troubled Viking Age, Arran became the property of the Norwegian crown, until formally absorbed by the kingdom of Scotland in the 13th century.
The 19th-century "clearances" led to significant depopulation and the end of the Gaelic language and way of life. The economy and population have recovered in the main industry being tourism. There is a diversity including three species of tree endemic to the area; the island includes miles of coastal pathways, numerous hills and mountains, forested areas, small lochs and beaches. Its main beaches are at Brodick, Whiting Bay, Kildonan and Blackwaterfoot. Most of the islands of Scotland have been occupied consecutively by speakers of at least four languages since the Iron Age. Many of the names of these islands have more than one possible meaning as a result. Arran is therefore not unusual in. Mac an Tàilleir states that "it is said to be unrelated to the name Aran in Ireland". Unusually for a Scottish island, Haswell-Smith offers a Brythonic derivation and a meaning of "high place" which at least corresponds with the geography — Arran is loftier than all the land that surrounds it along the shores of the Firth of Clyde.
Any other Brythonic place-names that may have existed were replaced on Arran as the Goidelic-speaking Gaels spread from Ireland, via their adjacent kingdom of Dál Riata. During the Viking Age it became, along with most Scottish islands, the property of the Norwegian crown, at which time it may have been known as "Herrey" or "Hersey"; as a result of this Norse influence, many current place-names on Arran are of Viking origin. The island lies in the Firth of Clyde between Ayr and Ardrossan, Kintyre; the profile of the north Arran hills as seen from the Ayrshire coast is referred to as the "Sleeping Warrior", due to its resemblance to a resting human figure. The highest of these hills is Goat Fell at 873.5 metres. There are three other Corbetts, all in the north east: Cìr Mhòr and Beinn Tarsuinn. Beinn Bharrain is the highest peak in the north west at 721 metres; the largest glen on the island is Glen Iorsa to the west, whilst narrow Glen Sannox and Glen Rosa to the east surround Goat Fell. The terrain to the south is less mountainous, although a considerable portion of the interior lies above 350 metres, A' Chruach reaches 512 metres at its summit.
There are two other Marilyns in the south and Mullach Mòr. Arran has several villages around the shoreline. Brodick is the site of the ferry terminal, several hotels, the majority of shops. Brodick Castle is a seat of the Dukes of Hamilton. Lamlash, however, is the largest village on the island and in 2001 had a population of 1,010 compared to 621 for Brodick. Other villages include Lochranza and Catacol in the north, Corrie in the north east, Blackwaterfoot in the south west, Kildonan in the south and Whiting Bay in the south east. Arran has three smaller satellite islands: Holy Isle lies to the east opposite Lamlash, Pladda is located off Arran's south coast and tiny Hamilton Isle lies just off Clauchlands Point 1.2 kilometres north of Holy Isle. Eilean na h-Àirde Bàine off the south west of Arran at Corriecravie is a skerry connected to Arran at low tide. Other islands in the Firth of Clyde include Great Cumbrae and Inchmarnock; the division between the "Highland" and "Lowland" areas of Arran is marked by the Highland Boundary Fault which runs north east to south west across Scotland.
Arran is a popular destination for geologists, who come to see intrusive igneous landforms such as sills and dykes, sedimentary and meta-sedimentary rocks ranging in age from Precambrian to Mesozoic. Most of the interior of the northern half of the island is taken up by a large granite batholith, created by substantial magmatic activity around 58 million years ago in the Paleogene period; this comprises an outer ring of coarse granite and an inner core of finer grained granite, intruded later. This granite was intruded into the Late Proterozoic to Cambrian metasediments of the Dalradian Supergroup. Other Paleogene igneous rocks on Arran include extensive felsic and composite sills in the south of the island, the central ring complex, an eroded caldera system surrounded by a near-continuous ring of granitic rocks. Sedimentary rocks dominate the southern half of the island Old and New Red Sandstone; some of these sandstones contain fulgurites – pitted marks that may have been created by Permian lightning strikes.
Large aeolian sand dunes are preserved in Permian sandstones near Brodick, showing the presence of an ancient desert. Within the central complex are subsided blocks o
Inchcailloch is an island on Loch Lomond in Scotland. It is 85 m at its highest point, it is known to some as Inchebroida. The name Inchcailloch means "Isle of the old woman" or "Isle of the Cowled Woman" in the Scottish Gaelic language. Saint Kentigerna went to Scotland from Ireland to preach and spread Christianity and the island is thought to be named after her. Inchmurrin, Creinch and Inchcailloch all form part of the Highland boundary fault. There is a burial ground in the north of the island, a bay, Port Bawn, in the south. Like many of the Loch Lomond islands, it is quite wooded. There is a passenger ferry across the short channel separating it from Balmaha on the mainland; as a result, it receives more visitors than most of the Loch Lomond islands 20,000 visitors per year. There is a camp site in the south at a nature trail. Inchcailloch has been used as a hunting forest since the reign of Robert the Bruce. Deer still roam the island. White deer have been seen on the island in 2003; the narrow crossing is shallow making an easy passage for deer to ford.
The island was farmed until the early 19th century, being recorded in 1800 as producing good wheat and oats. For around 130 years, Inchcailloch was an oak plantation; the resulting timber was processed at Balmaha, for making wood vinegar, wood tar, dye. Inchcailloch had a church dedicated to St Kentigerna, the parish church until 1621, but the graveyard was used until 1947. St Kentigerna was an Irish woman, not to be confused with St Kentigern; the Clan MacGregor burial ground includes some of Rob Roy's ancestors. Legends have passed by word of mouth that the bones of a woman were found under the altar stone during an excavation. Inchcailloch forms part of Loch Lomond National Nature Reserve and run by Scottish Natural Heritage. Inchcailloch is mentioned in Dr William Fraser's The Lennox; the travel writer, H. V. Morton visited in the 1930s, remarked: The isle is sacred to the MacGregors, in the tangled branches and amongst the green trees is their ancient burial ground, it was on the halidom of him'who sleeps beneath the grey stone of Inchcailloch' that members of this vigorous clan used to take their oaths.
Walter Scott refers to the island in his poem, The Lady of the Lake - A slender crosslet formed with care A cubit's length in measure due The shafts and limbs were rods of yew Whose parents in Inch Cailliach wave Their Shadows o'er Clan Alpine's grave, answering Lomond's breezes deep, Soothe many a chieftain's endless sleep. Https://web.archive.org/web/20090710015304/http://lochlomond-islands.com/ article which mentions it
In geology, a graben is a depressed block of the crust of a planet bordered by parallel faults. Graben is German for trench; the plural form is either grabens. A graben is a valley with a distinct escarpment on each side caused by the displacement of a block of land downward. Graben occur side-by-side with horsts. Horst and graben structures indicate crustal stretching. Graben are produced from parallel normal faults, where the displacement of the hanging wall is downward, while that of the footwall is upward; the faults dip toward the center of the graben from both sides. Horsts are parallel blocks. Single or multiple graben can produce a rift valley. In many rifts, the graben are asymmetric, with a major fault along only one of the boundaries, these are known as half-graben; the polarity of the main bounding faults alternates along the length of the rift. The asymmetry of a half-graben affects syntectonic deposition. Comparatively little sediment enters the half-graben across the main bounding fault because of footwall uplift on the drainage systems.
The exception is at any major offset in the bounding fault, where a relay ramp may provide an important sediment input point. Most of the sediment will enter the half-graben down the unfaulted hanging wall side. Lambert Graben, Antarctica East African Rift Valley Lucapa Graben, Lunda Norte Province, Angola Narmada River Valley, central India lower Godavari River Valley, southern India Baikal Rift Zone, Russia Moma Graben, Sakha Republic, Russia Büyük Menderes Graben, Turkey Unzen Graben, Japan Rhine valley, border area of west Germany and northeast France Oslo graben around Oslo, Norway Central Lowlands, Scotland Worcester Basin, England Central Graben, North Sea Viking Graben, North Sea Saguenay Graben, Canada Ottawa-Bonnechere Graben and Quebec, Canada Basin and Range Province of southwestern North America is an example of multiple horst/graben structures, including Death Valley, with Salt Lake Valley being the easternmost and Owens Valley being the westernmost. Rio Grande Rift Valley in Colorado/New Mexico/Texas of the United States Lake Tahoe Basin and Nevada, U.
S. Lake George Basin, New York, U. S. Santa Clara Valley, California, U. S. Republic Graben, Washington, U. S. Rough Creek Graben, Kentucky, U. S. Guatemala City valley, Guatemala Gulf St Vincent, South Australia Guanabara Graben, Rio de Janeiro, Brazil Fossa
An ophiolite is a section of the Earth's oceanic crust and the underlying upper mantle, uplifted and exposed above sea level and emplaced onto continental crustal rocks. Ophio is Greek for snake, lite means stone, after the green-color rocks that make up many ophiolites, their great significance relates to their occurrence within mountain belts such as the Alps and the Himalayas, where they document the existence of former ocean basins that have now been consumed by subduction. This insight was one of the founding pillars of plate tectonics, ophiolites have always played a central role in plate tectonic theory and the interpretation of ancient mountain belts; the stratigraphic-like sequence observed in ophiolites corresponds to the lithosphere-forming processes at mid-oceanic ridges: Sediments: muds and cherts deposited since the crust formed. Extrusive sequence: basaltic pillow lavas show magma/seawater contact. Sheeted dike complex: vertical, parallel dikes that fed lavas above. High level intrusives: isotropic gabbro, indicative of fractionated magma chamber.
Layered gabbro, resulting from settling out of minerals from a magma chamber. Cumulate peridotite: dunite-rich layers of minerals that settled out from a magma chamber. Tectonized peridotite: harzburgite/lherzolite-rich mantle rock; the Penrose field conference on ophiolites in 1972 redefined the term ophiolite to include only the igneous rocks listed above, excluding the sediments formed independently of the crust they sit on. This definition has been challenged because new studies of oceanic crust by the Integrated Ocean Drilling Program and other research cruises have shown that in situ ocean crust can be quite variable, that in places volcanic rocks sit directly on peridotite tectonite, with no intervening gabbros. Scientists have drilled only about 1.5 km into the 6- to 7-kilometer-thick oceanic crust, so their understanding of oceanic crust comes from comparing ophiolite structure to seismic soundings of in situ oceanic crust. Oceanic crust has a layered velocity structure that implies a layered rock series similar to that listed above.
In detail there are problems, with many ophiolites exhibiting thinner accumulations of igneous rock than are inferred for oceanic crust. Another problem relating oceanic crust and ophiolites is that the thick gabbro layer of ophiolites calls for large magma chambers beneath mid-ocean ridges. Seismic sounding of mid-ocean ridges has revealed only a few magma chambers beneath ridges, these are quite thin. A few deep drill holes into oceanic crust have intercepted gabbro, but it is not layered like ophiolite gabbro; the circulation of hydrothermal fluids through young oceanic crust causes serpentinization, alteration of the peridotites and alteration of minerals in the gabbros and basalts to lower temperature assemblages. For example, plagioclase and olivine in the sheeted dikes and lavas will alter to albite and serpentine, respectively. Ore bodies such as iron-rich sulfide deposits are found above altered epidosites that are evidence of black smokers, which continue to operate within the seafloor spreading centers of ocean ridges today.
Thus there is reason to crust. Compositional differences regarding silica and titania contents, for example, place ophiolite basalts in the domain of subduction zones, whereas mid-ocean ridge basalts have ~50% silica and 1.5–2.5% TiO2. These chemical differences extend to a range of trace elements as well. In particular, trace elements associated with subduction zone volcanics tend to be high in ophiolites, whereas trace elements that are high in ocean ridge basalts but low in subduction zone volcanics are low in ophiolites; the crystallization order of feldspar and pyroxene in the gabbros is reversed, ophiolites appear to have a multi-phase magmatic complexity on par with subduction zones. Indeed, there is increasing evidence that most ophiolites are generated when subduction begins and thus represent fragments of fore-arc lithosphere; this led to introduction of the term "supra-subduction zone" ophiolite in the 1980s to acknowledge that some ophiolites are more related to island arcs than ocean ridges.
Some of the classic ophiolite occurrences thought of as being related to seafloor spreading were found to be "SSZ" ophiolites, formed by rapid extension of fore-arc crust during subduction initiation. A fore-arc setting for most ophiolites solves the otherwise-perplexing problem of how oceanic lithosphere can be emplaced on top of continental crust, it appears that continental accretion sediments, if carried by the downgoing plate into a subduction zone, will jam it up and cause subduction to cease, resulting in the rebound of the accretionary prism with fore-arc lithosphere on top of it. Ophiolites with compositions comparable with hotspot-type eruptive settings or normal mid-oceanic ridge basalt are rare, those examples are strongly dismembered in subduction zone accretionary complexes. Ophiolites are common in orogenic belts of Mesozoic age, like those formed by the closure of the Tethys Ocean. Ophiolites in Archean and Paleoproterozoic domains are rare. Most ophiolites can be divided into one of two groups: Cordilleran.
Tethyan ophiolites are characteristic of those that occur in the eastern Mediterranean sea area, e.g. Troodos in Cyprus and in the Middle East such as Semail in Oman, which consist of complete
The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, 419.2 million years ago, to the beginning of the Carboniferous, 358.9 Mya. It is named after Devon, where rocks from this period were first studied; the first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods became well-established. Fish reached substantial diversity during this time, leading the Devonian to be dubbed the "Age of Fishes." The first ray-finned and lobe-finned bony fish appeared, while the placoderms began dominating every known aquatic environment. The ancestors of all four-limbed vertebrates began adapting to walking on land, as their strong pectoral and pelvic fins evolved into legs.
In the oceans, primitive sharks became more numerous than in the Late Ordovician. The first ammonites, species of molluscs, appeared. Trilobites, the mollusc-like brachiopods and the great coral reefs, were still common; the Late Devonian extinction which started about 375 million years ago affected marine life, killing off all placodermi, all trilobites, save for a few species of the order Proetida. The palaeogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, the early formation of the small continent of Euramerica in between; the period is named after Devon, a county in southwestern England, where a controversial argument in the 1830s over the age and structure of the rocks found distributed throughout the county was resolved by the definition of the Devonian period in the geological timescale. The Great Devonian Controversy was a long period of vigorous argument and counter-argument between the main protagonists of Roderick Murchison with Adam Sedgwick against Henry De la Beche supported by George Bellas Greenough.
Murchison and Sedgwick named the period they proposed as the Devonian System. While the rock beds that define the start and end of the Devonian period are well identified, the exact dates are uncertain. According to the International Commission on Stratigraphy, the Devonian extends from the end of the Silurian 419.2 Mya, to the beginning of the Carboniferous 358.9 Mya. In nineteenth-century texts the Devonian has been called the "Old Red Age", after the red and brown terrestrial deposits known in the United Kingdom as the Old Red Sandstone in which early fossil discoveries were found. Another common term is "Age of the Fishes", referring to the evolution of several major groups of fish that took place during the period. Older literature on the Anglo-Welsh basin divides it into the Downtonian, Dittonian and Farlovian stages, the latter three of which are placed in the Devonian; the Devonian has erroneously been characterised as a "greenhouse age", due to sampling bias: most of the early Devonian-age discoveries came from the strata of western Europe and eastern North America, which at the time straddled the Equator as part of the supercontinent of Euramerica where fossil signatures of widespread reefs indicate tropical climates that were warm and moderately humid but in fact the climate in the Devonian differed during its epochs and between geographic regions.
For example, during the Early Devonian, arid conditions were prevalent through much of the world including Siberia, North America, China, but Africa and South America had a warm temperate climate. In the Late Devonian, by contrast, arid conditions were less prevalent across the world and temperate climates were more common; the Devonian Period is formally broken into Early and Late subdivisions. The rocks corresponding to those epochs are referred to as belonging to the Lower and Upper parts of the Devonian System. Early DevonianThe Early Devonian lasted from 419.2 ± 2.8 to 393.3 ± 2.5 and began with the Lochkovian stage, which lasted until the Pragian. It spanned from 410.8 ± 2.8 to 407.6 ± 2.5, was followed by the Emsian, which lasted until the Middle Devonian began, 393.3± 2.7 million years ago. During this time, the first ammonoids appeared. Ammonoids during this time period differed little from their nautiloid counterparts; these ammonoids belong to the order Agoniatitida, which in epochs evolved to new ammonoid orders, for example Goniatitida and Clymeniida.
This class of cephalopod molluscs would dominate the marine fauna until the beginning of the Mesozoic era. Middle DevonianThe Middle Devonian comprised two subdivisions: first the Eifelian, which gave way to the Givetian 387.7± 2.7 million years ago. During this time the jawless agnathan fishes began to decline in diversity in freshwater and marine environments due to drastic environmental changes and due to the increasing competition and diversity of jawed fishes; the shallow, oxygen-depleted waters of Devonian inland lakes, surrounded by primitive plants, provided the environment necessary for certain early fish to develop such essential characteristics as well developed lungs, the ability to crawl out of the water and onto the land for short periods of time. Late DevonianFinally, the Late Devonian started with the Frasnian, 382.7 ± 2.8 to 372.2 ± 2.5, during which the first forests took shape on land. The first tetrapods appeared in the fossil record in the ensuing Famennian subdivisi
The Highlands is a historic region of Scotland. Culturally, the Highlands and the Lowlands diverged from the Middle Ages into the modern period, when Lowland Scots replaced Scottish Gaelic throughout most of the Lowlands; the term is used for the area north and west of the Highland Boundary Fault, although the exact boundaries are not defined to the east. The Great Glen divides the Grampian Mountains to the southeast from the Northwest Highlands; the Scottish Gaelic name of A' Ghàidhealtachd means "the place of the Gaels" and traditionally, from a Gaelic-speaking point of view, includes both the Western Isles and the Highlands. The area is sparsely populated, with many mountain ranges dominating the region, includes the highest mountain in the British Isles, Ben Nevis. Before the 19th century the Highlands was home to a much larger population, but from circa 1841 and for the next 160 years, the natural increase in population was exceeded by emigration and migration to the industrial cities of Scotland and England.
The area is now one of the most sparsely populated in Europe. At 9.1 per km2 in 2012, the population density in the Highlands and Islands is less than one seventh of Scotland's as a whole, comparable with that of Bolivia and Russia. The Highland Council is the administrative body for much of the Highlands, with its administrative centre at Inverness. However, the Highlands includes parts of the council areas of Aberdeenshire, Angus and Bute, North Ayrshire and Kinross, Stirling and West Dunbartonshire; the Scottish highlands is the only area in the British Isles to have the taiga biome as it features concentrated populations of Scots pine forest: see Caledonian Forest. Between the 15th century and the 20th century, the area differed from most of the Lowlands in terms of language. In Scottish Gaelic, the region is known as the Gàidhealtachd, because it was traditionally the Gaelic-speaking part of Scotland, although the language is now confined to The Hebrides; the terms are sometimes used interchangeably but have different meanings in their respective languages.
Scottish English is the predominant language of the area today, though Highland English has been influenced by Gaelic speech to a significant extent. The "Highland line" distinguished the two Scottish cultures. While the Highland line broadly followed the geography of the Grampians in the south, it continued in the north, cutting off the north-eastern areas, Eastern Caithness and Shetland, from the more Gaelic Highlands and Hebrides; the major social unit of the Highlands was the clan. Scottish kings James VI, saw clans as a challenge to their authority. Following the Union of the Crowns, James VI had the military strength to back up any attempts to impose some control; the result was, in 1609, the Statutes of Iona which started the process of integrating clan leaders into Scottish society. The gradual changes continued into the 19th century, as clan chiefs thought of themselves less as patriarchal leaders of their people and more as commercial landlords; the first effect on the clansmen who were their tenants was the change to rents being payable in money rather than in kind.
Rents were increased as Highland landowners sought to increase their income. This was followed in the period 1760-1850, by agricultural improvement that involved clearance of the population to make way for large scale sheep farms. Displaced tenants were set up in crofting communities in the process; the crofts were intended not to provide all the needs of their occupiers. Crofters came to rely on seasonal migrant work in the Lowlands; this gave impetus to the learning of English, seen by many rural Gaelic speakers to be the essential "language of work". Older historiography attributes the collapse of the clan system to the aftermath of the Jacobite risings; this is now thought less influential by historians. Following the Jacobite rising of 1745 the British government enacted a series of laws to try to suppress the clan system, including bans on the bearing of arms and the wearing of tartan, limitations on the activities of the Scottish Episcopal Church. Most of this legislation was repealed by the end of the 18th century as the Jacobite threat subsided.
There was soon a rehabilitation of Highland culture. Tartan was adopted for Highland regiments in the British Army, which poor Highlanders joined in large numbers in the era of the Revolutionary and Napoleonic Wars. Tartan had been abandoned by the ordinary people of the region, but in the 1820s, tartan and the kilt were adopted by members of the social elite, not just in Scotland, but across Europe; the international craze for tartan, for idealising a romanticised Highlands, was set off by the Ossian cycle, further popularised by the works of Walter Scott. His "staging" of the visit of King George IV to Scotland in 1822 and the king's wearing of tartan resulted in a massive upsurge in demand for kilts and tartans that could not be met by the Scottish woollen industry. Individual clan tartans were designated in this period and they became a major symbol of Scottish identity; this "Highlandism", by which all of Scotland was identified with the culture of the Highlands, was cemented by Queen Victoria's interest in the country, her adoption of Balmoral as a major royal retreat, her interes