|
Loch Ness Supergroup
The Loch Ness Supergroup is one of the subdivisions of the Neoproterozoic sequence of sedimentary rocks (or their metamorphic equivalents) in the Scottish Highlands. It is found everywhere in tectonic contact above the older Wester Ross Supergroup. It is thought to be unconformably overlain by the Cryogenian to Cambrian Dalradian Supergroup. Stratigraphy The supergroup is subdivided into three groups. Glenfinnan Group This group, which consists of amphibolite facies pelitic gneiss and interbanded pelite, semi-pelite, psammite, quartzite and migmatites, lies tectonically above the Sgurr Beag Thrust and below the Loch Eil Group. There is evidence of a true stratigraphic transition between these two groups in some areas. Slices of Lewisian-type gneisses are found above the Sgurr Beag Thrust and are interpreted to represent pieces of basement to the group, with a highly sheared unconformable contact, incorporated during the Caledonian orogeny. The original stratigraphic thickness ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonian
The Tonian (from grc, τόνος, tónos, meaning "stretch") is the first geologic period of the Neoproterozoic era (geology), Era. It lasted from to Mya (million years ago). Instead of being based on stratigraphy, these dates are defined by the International Commission on Stratigraphy, ICS based on radiometric dating, radiometric chronometry. The Tonian is preceded by the Stenian Period of the Mesoproterozoic Era and followed by the Cryogenian. Rifting leading to the breakup of supercontinent Rodinia, which had formed in the mid-Stenian, occurred during this period, starting from 900 to 850 Mya. Biology The first putative metazoan (animal) fossils are dated to the middle to late Tonian ( 890-800 Mya). The fossils of ''Otavia antiqua'', which has been described as a sponge by its discoverers and numerous other scholars, date back to about 800 mya. Even earlier sponge-like fossils have been reported in reefs dating back to 890 million years before the present, but their ident ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelite
A pelite (Greek: ''pelos'', "clay") or metapelite is a metamorphosed fine-grained sedimentary rock, i.e. mudstone or siltstone. The term was earlier used by geologists to describe a clay-rich, fine-grained clastic sediment or sedimentary rock, i.e. mud or a mudstone, the metamorphosed version of which would technically have been a ''metapelite''. It was equivalent to the now little-used Latin-derived term lutite.Potter, P.E., J.B. Maynard, and P.J. Depetris (2005) ''Muds and Mudstones.'' New York, New York, Springer. 279 pp. Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. A semipelite is defined in part as having similar chemical composition but being of a crystalloblastic nature. Pettijohn (1975) gives the following descriptive terms based on grain size, avoiding the use of terms such as clay or argillaceous which carry an implication of chemical composition. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Detrital Zircon Geochronology
Detrital zircon geochronology is the science of analyzing the age of zircons deposited within a specific sedimentary unit by examining their inherent radioisotopes, most commonly the uranium–lead ratio. Zircon is a common accessory or trace mineral constituent of most granite and felsic igneous rocks. Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands. Zircons contain trace amounts of uranium and thorium and can be dated using several modern analytical techniques. Detrital zircon geochronology has become increasingly popular in geological studies from the 2000s mainly due to the advancement in radiometric dating techniques. Detrital zircon age data can be used to constrain the maximum depositional age, determine provenance, and reconstruct the tectonic setting on a regional scale. Detrital zircon Origin Detrital zircons are part of the sediment derived from weathering and erosion of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Newtonmore
Newtonmore ( gd, Baile Ùr an t-Sléibh ) is a village in the Highland council area of Scotland. The village is only a few miles from a location that is claimed to be the exact geographical centre of Scotland There is some debate as to the location of the geographical centre of Scotland. This is due to different methods of calculating the centre, and whether surrounding islands are included. Centre of gravity method In 2002, the Ordnance Survey calc .... Activities *Shinty - The town is renowned for having a shinty team, Newtonmore Camanachd Club, which plays at The Eilan next to the River Calder, Highland, River Calder. * Walking - Newtonmore calls itself the "Walking Centre of Scotland", referring both to its geographical location and to the great walking opportunities locally, like thWildcat Trail An extension to the Speyside Way could soon add Newtonmore to a Long Distance Route and it will become the new end to this trail. * Golf - Newtonmore has a golf course on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grantown-on-Spey
Grantown-on-Spey ( gd, Baile nan Granndach) is a town in the Highland Council Area, Counties of Scotland, historically within the county of Moray. It is located on a low plateau at Freuchie beside the river Spey at the northern edge of the Cairngorms, Cairngorm mountains, about south-east of Inverness ( by road). The town was founded in 1765 as a New town, planned settlement and was originally called simply Grantown after Sir James Grant, 8th Baronet, Sir James Grant. The addition 'on Spey' was added by the burgh council in 1898. The town has several listed 18th and 19th century buildings, including several large hotels and serves as a regional centre for tourism and services in the Strathspey, Scotland, Strathspey region. The town is twinned with Notre-Dame-de-Monts in the Vendée, Pays de la Loire, France. History The burgh was founded in 1765 during the early stages of the Industrial Revolution to encourage both agricultural marketing and handicrafts, as well as to increa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverness
Inverness (; from the gd, Inbhir Nis , meaning "Mouth of the River Ness"; sco, Innerness) is a city in the Scottish Highlands. It is the administrative centre for The Highland Council and is regarded as the capital of the Highlands. Historically it served as the county town of the county of Inverness-shire. Inverness lies near two important battle sites: the 11th-century battle of Blàr nam Fèinne against Norway which took place on the Aird, and the 18th century Battle of Culloden which took place on Culloden Moor. It is the northernmost city in the United Kingdom and lies within the Great Glen (Gleann Mòr) at its northeastern extremity where the River Ness enters the Beauly Firth. At the latest, a settlement was established by the 6th century with the first royal charter being granted by Dabíd mac Maíl Choluim (King David I) in the 12th century. Inverness and Inverness-shire are closely linked to various influential clans, including Clan Mackintosh, Clan Fraser and Cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strathglass
Strathglass is a strath or wide and shallow valley in the Northwest Highlands of Scotland down which runs the meandering River Glass from the point at which it starts at the confluence of the River Affric and Abhainn Deabhag to the point where, on joining with the River Farrar at Struy, the combined waters become the River Beauly. The A831 road runs southwest from the vicinity of Erchless Castle up the length of Strathglass and serves the village of Cannich which is the largest settlement within the valley. The road then runs east from here via Glen Urquhart to Drumnadrochit beside Loch Ness. A minor road continues southwest up the valley from Cannich towards Glen Affric. Strathglass was also followed by a line of electricity pylons but that has been replaced by a line of new pylons across Eskdale Moor to the east of the strath. Both flanks of the valley are heavily wooded; on the higher ground to the northwest, beyond the forests are the moors of Struy Forest and Balmore Fores ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Old Red Sandstone
The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also extends northwards into Greenland and Svalbard. These areas were a part of the ancient continent of Euramerica, Euramerica/Laurussia. In Britain it is a lithostratigraphy, lithostratigraphic unit (a sequence of rock strata) to which Stratigraphy, stratigraphers accord Geological unit#Lithostratigraphic units, supergroup status and which is of considerable importance to early paleontology. For convenience the short version of the term, ORS is often used in literature on the subject. The term was coined to distinguish the sequence from the younger New Red Sandstone which also occurs widely throughout Britain. Sedimentology The Old Red Sandstone describes a suite of sedimentary rocks deposited in a variety of environments during the Devonian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unconformity
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger layer, but the term is used to describe any break in the sedimentary geologic record. The significance of angular unconformity (see below) was shown by James Hutton, who found examples of Hutton's Unconformity at Jedburgh in 1787 and at Siccar Point in 1788. The rocks above an unconformity are younger than the rocks beneath (unless the sequence has been overturned). An unconformity represents time during which no sediments were preserved in a region or were subsequently eroded before the next deposition. The local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of geologic time not represented is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sgurr Beag Thrust
The Sgurr Beag Thrust is an important tectonic structure within the Neoproterozoic metasedimentary rock sequences of the Scottish Highlands. The thrust, or similar structures correlated with it, form the boundary between rocks of the Glennfinnan Group and the underlying Morar Group. It divides the Wester Ross Supergroup from the Loch Ness Supergroup. The history of this structure remains poorly understood although it is thought to be at least partly of Caledonian age. Extent The Sgurr Beag Thrust was identified as a zone of high strain in the western part of the Highlands and was originally called the "Sgurr Beag Slide". It is currently interpreted to extend from the Morvern peninsula in the southwest (with a possible extension onto the Isle of Mull), to the Dornoch Firth where it disappears beneath the Old Red Sandstone. It is often marked by the presence of inliers of Lewisian basement, which are found in its hanging-wall (structurally above the fault plane). In eastern Suther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Migmatite
Migmatite is a composite rock found in medium and high-grade metamorphic environments, commonly within Precambrian cratonic blocks. It consists of two or more constituents often layered repetitively: one layer is an older metamorphic rock that was reconstituted subsequently by partial melting ("paleosome"), while the alternate layer has a pegmatitic, aplitic, granitic or generally plutonic appearance ("neosome"). Commonly, migmatites occur below deformed metamorphic rocks that represent the base of eroded mountain chains. Migmatites form under extreme temperature and pressure conditions during prograde metamorphism, when partial melting occurs in metamorphic paleosome. Components exsolved by partial melting are called neosome (meaning ‘new body’), which may or may not be heterogeneous at the microscopic to macroscopic scale. Migmatites often appear as tightly, incoherently folded veins ( ptygmatic folds).Recommendations by the IUGS Subcommission on the Systematics of M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
