Kelvin Island (french: île Kelvin) is a large island in the centre of

Lake Nipigon Lake Nipigon (; french: lac Nipigon; oj, Animbiigoo-zaaga'igan) is part of the Great Lakes drainage basin. It is the largest lake entirely within the boundaries of the Canadian province of Ontario. Etymology In the Jesuit Relations the lake is ...

, in

Thunder Bay District Thunder Bay District is a district and census division in Northwestern Ontario in the Canadian province of Ontario. The district seat is Thunder Bay. In 2016, the population was 146,048. The land area is ; the population density was . Most ...

in northwestern

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central C ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

. It is named after the British scientist

William Thomson, 1st Baron Kelvin William Thomson, 1st Baron Kelvin, (26 June 182417 December 1907) was a British mathematician, Mathematical physics, mathematical physicist and engineer born in Belfast. Professor of Natural Philosophy (Glasgow), Professor of Natural Philoso ...

(1824–1907). The island has an area of about . Frith Lake lies in the centre of the island, and there are six other unnamed lakes. Henry's Harbour is at the western tip, and Moose's Harbour is the middle on the eastern side.

Geology

Geologic mapping A geologic map or geological map is a special-purpose map made to show various geological features. Rock units or geologic strata are shown by color or symbols. Bedding planes and structural features such as faults, folds, are shown with s ...

of Kelvin Island in the 1980s found it to consist almost entirely of Proterozoic diabase. Cliffs and other

outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficia ...

s along the shoreline of Kelvin Island expose predominately massive, medium-grained diabase and subordinate layered diabase. Shoreline exposures of

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

, amphibole diabase, poikilitic diabase, and diabase with

pegmatitic A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ...

patches or

veins Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...

are uncommon. Only a single exposure each of

anorthositic Anorthosite () is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minera ...

diabase and

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an ad ...

mudstone was mapped. An exposure of fine-grained, columnar jointed diabase is associated with the exposure of calcareous mudstone. Regional geologic mapping of the northern part of Lake Nipigon region indicates that the diabase underlying Kelvin Island are parts of a single igneous sill approximately thick. This sill grades from its base to top in a series of layers consisting of: 1.) a basal lower chill zone, 2.) coarse poikilitic diabase to medium-grained diabase, 3.) medium-grained diabase with coarse pegmatitic patches, and 4.) an upper of fine-grained to aphanitic diabase with columnar joints and is locally vesicular. The layer of medium-grained diabase locally displays igneous layering and contains zones of anorthosltic diabase. This sill is one of several diabase sills,

cone sheet A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines conn ...

s, and

dikes Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes ...

, which are collectively known as either the Logan or Nipigon sills, that form extensive rock exposures in the northern part of Lake Nipigon region. These dikes and sills intrude Proterozoic

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

s, largely

quartz arenite A quartz arenite or quartzarenite is a sandstone composed of greater than 90% detrital quartz. Quartz arenites are the most mature sedimentary rocks possible, and are often referred to as ultra- or super-mature, and are usually cemented by sili ...

s and mudstones known as the Sibley Group.

Agate Agate () is a common rock formation, consisting of chalcedony and quartz as its primary components, with a wide variety of colors. Agates are primarily formed within volcanic and metamorphic rocks. The ornamental use of agate was common in Anci ...

s have reportedly been found on the beach along West Bay, which lies on the western shore of Lake Nipigon and west of Kelvin Island. Like the shoreline of Kelvin Island, the shoreline of West Bay consists largely of medium-grained diabase of the Nipigon sills.

Ecology

In 1964 the island had an estimated moose population of 0.48 for each as counted from the air. Pellet group counts may give a higher estimate. Also and . Kelvin Island is part of the Lake Nipigon Conservation Reserve.

References

{{DEFAULTSORT:Kelvin Island Lake islands of Ontario