Glossary

Gneiss

Fact Sheet:

Chemical Composition: Variable; primarily composed of feldspar, quartz, and mica, with minor amounts of other minerals such as amphibole and garnet
Hardness: 6 to 7 on the Mohs scale
Crystal System: Metamorphic rock (not crystalline in the same way as minerals)
Color Varieties: Banded or foliated, typically gray, pink, white, and black, with alternating light and dark mineral layers
Major Localities: United States, Canada, Norway, Scotland, India, and South Africa
Common Uses: Building material, decorative stone, aggregate for roads, and landscaping

Introduction: Gneiss (pronounced “nice”) is one of the most common metamorphic rocks in the ...

^IInfiltration

Infiltration is the process by which water on the ground surface enters the soil. It is a critical component of the hydrological cycle, influencing groundwater recharge, soil moisture, and surface runoff. Understanding infiltration is essential for water resource management, agriculture, and erosion control.

Reference: Hillel, D. (1998). Environmental Soil Physics. Academic Press.

^JJacket (Oil Platform)

A jacket is the steel framework supporting offshore oil platforms, designed to withstand harsh marine environments. The jacket is driven into the seabed to provide stability for the platform. Understanding the design and function of jackets is crucial in offshore engineering, the development of oil and gas resources, and the safety of marine structures.

Reference: Palmer, A. C., & King, R. A. (2008). “Subsea Pipeline Engineering.” PennWell Books.

^JJade Belt

A jade belt refers to a region or zone rich in jade deposits, often associated with tectonic settings where high-pressure, low-temperature metamorphism occurs. These belts are significant in economic geology for jade mining and in studying the geological conditions that lead to jade formation.

Reference: Harlow, G. E., & Sorensen, S. S. (2005). “Jade (Jadeitite and Nephrite) and Serpentinite: Metasomatic Connections.” International Geology Review, 47(2), 113-146.

^JJet (Lignite)

Jet is a compact form of lignite, a type of brown coal, which can be polished and used as a gemstone. It forms from the decomposition of wood under extreme pressure and is known for its deep black color. Jet has been used since prehistoric times for jewelry and ornamental objects and is significant in understanding the early use of coal and organic material in geology.

Reference: Scott, A. C., & Glasspool, I. J. (2007). “Observations and Experiments on the Origin and Formation of Inertinite Group Macerals.” International Journal of Coal Geology, 70(1-3), 53-66.

^JJetty

A jetty is a structure built from the shore into a body of water to influence currents or protect a harbor. Jetties are significant in coastal engineering, sediment transport studies, and the management of coastal erosion. They can also impact local ecosystems by altering water flow and sediment deposition patterns.

Reference: Dean, R. G. (2003). Beach Nourishment: Theory and Practice. World Scientific.

^JJig (Mining)

A jig is a mining device used to separate minerals from ore based on differences in density. The jigging process involves pulsating water that causes the heavier minerals to settle and the lighter waste material to rise. Jigs are important in mineral processing for recovering valuable minerals and improving ore grades.

Reference: Wills, B. A., & Finch, J. (2015). Wills’ Mineral Processing Technology: An Introduction to the Practical Aspects of Ore Treatment and Mineral Recovery. Butterworth-Heinemann.

^JJoint (Geology)

A joint is a fracture or crack in a rock along which there has been no significant movement parallel to the plane of the fracture. Joints are common in many rock types and often occur in sets or systems. They are important in studying the mechanical behavior of rocks, the movement of groundwater, and the formation of geological structures.

Reference: Pollard, D. D., & Aydin, A. (1988). “Progress in Understanding Jointing Over the Past Century.” Geological Society of America Bulletin, 100(8), 1181-1204.

^JJökulhlaup

A jökulhlaup is a type of glacial outburst flood that occurs when water trapped by a glacier or within a glacial lake is suddenly released. These floods can cause significant erosion, transport large amounts of sediment, and have major impacts on landscapes. Jökulhlaups are important in understanding glacial processes, flood dynamics, and landscape evolution.

Reference: Björnsson, H. (2002). “Subglacial Lakes and Jökulhlaups in Iceland.” Global and Planetary Change, 35(3-4), 255-271.

^JJökulsárgljúfur

Jökulsárgljúfur is a canyon in Iceland formed by the Jökulsá á Fjöllum river, known for its dramatic landscapes, including waterfalls, cliffs, and basalt formations. The canyon was shaped by a combination of glacial meltwater floods and volcanic activity, making it significant for studying geomorphology, glacial processes, and volcanic landscapes.

Reference: Tómasson, H. (1993). “Jökulsárgljúfur—A Canyon Formed by a Series of Catastrophic Floods.” Geografiska Annaler: Series A, Physical Geography, 75(1-2), 101-113.

^JJominy End-Quench Test

The Jominy end-quench test is a method used to determine the hardenability of steel by observing the hardness gradient along a sample after it has been heated and quenched at one end. This test is important in materials science and metallurgical engineering for understanding the properties of different steel compositions and their suitability for various applications.

Reference: Grossmann, M. A., & Bain, E. C. (1938). “Principles of Heat Treatment.” American Society for Metals.

^JJovian Planets

Jovian planets, also known as gas giants, are large planets primarily composed of hydrogen and helium, with thick atmospheres and no well-defined solid surface. The Jovian planets in our solar system are Jupiter, Saturn, Uranus, and Neptune. Studying Jovian planets is important in planetary science for understanding the formation and evolution of planetary systems.

Reference: Guillot, T. (2005). “The Interiors of Giant Planets: Models and Outstanding Questions.” Annual Review of Earth and Planetary Sciences, 33, 493-530.

^JJura Limestone

Jura Limestone is a type of limestone that forms part of the Jura Mountains, which extend along the border between France and Switzerland. This limestone is known for its high fossil content, particularly of marine organisms from the Jurassic period. Jura Limestone is important in paleontology, stratigraphy, and as a building material.

Reference: Hofmann, H. J., & Riding, R. (1978). “Fossil Stromatolites from the Jurassic of the Canadian Cordillera.” Geological Society of America Bulletin, 89(2), 321-329.

^JJura Mountains

The Jura Mountains are a sub-alpine mountain range located on the border between France and Switzerland, known for their folded limestone formations. The Jura Mountains are significant in studying the tectonic processes of mountain building, the stratigraphy of the Mesozoic era, and the development of karst landscapes.

Reference: Becker, A. (2000). “The Jura Mountains—An Active Fold-and-Thrust Belt?” Tectonophysics, 321(1), 381-406.

^JJura-Cretaceous Boundary

The Jura-Cretaceous boundary marks the transition between the Jurassic and Cretaceous periods, approximately 145 million years ago. This boundary is characterized by significant changes in faunal assemblages and global climate. Understanding this boundary is important for studying the evolution of life, paleoclimate, and the geological history of the Mesozoic era.

Reference: Ogg, J. G., & Hinnov, L. A. (2012). “Jurassic.” In: Gradstein, F. M., Ogg, J. G., Schmitz, M., & Ogg, G. (Eds.), The Geologic Time Scale 2012. Elsevier, pp. 731-791.

^JJurassic Carbonate Platforms

Jurassic carbonate platforms are extensive, shallow marine environments where carbonate sediments, primarily composed of calcium carbonate, were deposited during the Jurassic period. These platforms are significant for understanding ancient marine ecosystems, sedimentary processes, and the evolution of reef-building organisms.

Reference: Leinfelder, R. R., et al. (1994). “Jurassic Reef and Platform Facies and their Global Correlation.” In: International Symposium on Fossil Cnidaria including Archaeocyatha and Porifera.

^JJurassic Coast

The Jurassic Coast is a World Heritage Site on the southern coast of England, famous for its geological formations that span the Triassic, Jurassic, and Cretaceous periods. It provides an exceptional record of Earth’s history, particularly the fossil record of marine life from the Jurassic period. The site is important for understanding the geological history of the Earth and the processes of coastal erosion.

Reference: West, I. M. (2014). Geology of the Jurassic Coast. Geological Conservation Review Series, Natural England.

^JJuvenile Water

Juvenile water refers to water that is released from magma during volcanic activity and is not part of the existing hydrological cycle. This water originates from the Earth’s mantle and is considered “new” to the Earth’s surface environment. Juvenile water is important in volcanology, hydrogeology, and the study of the Earth’s deep water cycle.

Reference: Fyfe, W. S., Price, N. J., & Thompson, A. B. (1978). Fluids in the Earth’s Crust: Their Significance in Metamorphic, Tectonic and Chemical Transport Processes. Elsevier.

^KK-T Boundary (Cretaceous-Paleogene Boundary)

The K-T boundary, now referred to as the Cretaceous-Paleogene (K-Pg) boundary, marks the transition between the Cretaceous and Paleogene periods around 66 million years ago. It is associated with a mass extinction event that wiped out approximately 75% of Earth’s species, including the dinosaurs. The boundary is often identified by a layer of iridium-rich clay.

Reference: Schulte, P., et al. (2010). “The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary.” Science, 327(5970), 1214-1218.

^KKaapvaal Craton

The Kaapvaal Craton is an ancient geological formation in southern Africa, one of the Earth’s oldest and most stable continental cratons, dating back over 3 billion years. It is significant in studying the formation and stabilization of continental crust, as well as in understanding the early history of the Earth’s lithosphere.

Reference: De Wit, M. J., & Ashwal, L. D. (1997). “Greenstone Belts: Ancient Crustal Analogues.” Oxford University Press.

^KKame

A kame is a mound or hill of sand and gravel deposited by meltwater streams in glacial environments. Kames form in depressions or cavities on or within glaciers and are often found in clusters called kame fields. They are important in reconstructing past glacial environments and understanding sediment transport by meltwater.

Reference: Easterbrook, D. J. (1999). “Surface Processes and Landforms.” Prentice Hall.

^KKarakoram Range

The Karakoram Range is a major mountain range spanning the borders between Pakistan, India, and China, and includes some of the world’s highest peaks, such as K2. The range is significant for its complex geology, including active tectonics, glaciation, and unique biodiversity. It is a key area for studying mountain building processes and the impacts of climate change on glaciers.

Reference: Searle, M. P. (1991). “Geology and Tectonics of the Karakoram Mountains.” Wiley.

^KKaroo Basin

The Karoo Basin is a large sedimentary basin in South Africa, known for its extensive Permian to Jurassic sedimentary rocks and rich fossil record, including early dinosaurs and synapsids. The basin is important in studying the Permian-Triassic extinction event, the evolution of early terrestrial ecosystems, and the development of large continental basins.

Reference: Catuneanu, O., et al. (2005). “The Karoo Basins of South-Central Africa.” Journal of African Earth Sciences, 43(1-3), 211-253.

^KKarst

Karst is a type of landscape formed by the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by features such as sinkholes, caves, and underground drainage systems. Karst landscapes are significant in hydrogeology for understanding groundwater flow, the formation of aquifers, and the unique ecosystems that develop in such environments.

Reference: Ford, D., & Williams, P. (2007). “Karst Hydrogeology and Geomorphology.” Wiley.

^TArchives: Glossary

A transcurrent fault is a type of strike-slip fault where the motion is predominantly horizontal, with little vertical displacement. These faults are significant in tectonics for understanding lateral movements of the Earth’s crust, the formation of fault zones, and the seismic activity associated with these faults.

Reference: Sylvester, A. G. (1988). “Strike-Slip Faults.” Geological Society of America Bulletin, 100(11), 1666-1703.

Rocks

Glossary

I

Infiltration

J

Jacket (Oil Platform)

J

Jade Belt

J

Jet (Lignite)

J

Jetty

J

Jig (Mining)

J

Joint (Geology)

J

Jökulhlaup

J

Jökulsárgljúfur

J

Jominy End-Quench Test

J

Jovian Planets

J

Jura Limestone

J

Jura Mountains

J

Jura-Cretaceous Boundary

J

Jurassic Carbonate Platforms

J

Jurassic Coast

J

Juvenile Water

K

K-T Boundary (Cretaceous-Paleogene Boundary)

K

Kaapvaal Craton

K

Kame

K

Karakoram Range

K

Karoo Basin

K

Karst

Gneiss

IInfiltration

JJacket (Oil Platform)

JJade Belt

JJet (Lignite)

JJetty

JJig (Mining)

JJoint (Geology)

JJökulhlaup

JJökulsárgljúfur

JJominy End-Quench Test

JJovian Planets

JJura Limestone

JJura Mountains

JJura-Cretaceous Boundary

JJurassic Carbonate Platforms

JJurassic Coast

JJuvenile Water

KK-T Boundary (Cretaceous-Paleogene Boundary)

KKaapvaal Craton

KKame

KKarakoram Range

KKaroo Basin

KKarst

TArchives: Glossary