Glossary

Galena

Fact Sheet:

Chemical Composition: PbS (Lead Sulfide)
Hardness: 2.5 on the Mohs scale
Crystal System: Cubic
Color Varieties: Lead-gray, silver-gray
Major Localities: United States, Mexico, Germany, Australia, Peru, and the UK
Common Uses: Primary ore of lead, source of silver, industrial materials, lead-acid batteries, and radiation shielding

Introduction: Galena is the most important lead ore and one of the most abundant and widely distributed sulfide minerals. Its distinctive metallic luster and high density make it easy to identify, and its cubic crystal form is iconic. Beyond its significance as a lead ore, galena is also a major ...

^RRipple Marks

Ripple marks are small, wave-like structures formed on the surface of sedimentary rocks by the action of water or wind. They are significant in sedimentology for interpreting past environments, including the direction of water flow or wind, and for understanding the conditions under which sediments were deposited.

Reference: Reineck, H.-E., & Singh, I. B. (1980). “Depositional Sedimentary Environments.” Springer-Verlag.

^RRock Glacier

A rock glacier is a mass of rock, ice, and debris that moves slowly downhill, similar to a glacier. Rock glaciers are significant for understanding periglacial environments, the movement of ice and debris in cold climates, and the geomorphic processes shaping mountainous regions.

Reference: Barsch, D. (1996). “Rock Glaciers: Indicators for the Present and Former Geoecology in High Mountain Environments.” Springer.

^RRodinia

Rodinia was a supercontinent that existed during the Neoproterozoic era, approximately 1.3 billion to 750 million years ago. The study of Rodinia is significant for understanding the assembly and breakup of supercontinents, the evolution of Earth’s tectonic plates, and the environmental changes that led to the Snowball Earth events.

Reference: Dalziel, I. W. D. (1997). “Neoproterozoic-Paleozoic Geography and Tectonics: Review, Hypothesis, Environmental Speculation.” Geological Society of America Bulletin, 109(1), 16-42.

^SSalt Dome

A salt dome is a type of structural dome formed when a thick bed of evaporite minerals, mainly salt, intrudes vertically through overlying rock layers. Salt domes are significant in petroleum geology for trapping hydrocarbons and as targets for oil and gas exploration.

Reference: Jackson, M. P. A., & Talbot, C. J. (1986). “External Shapes, Strains, and Deformations of Salt Structures.” Geological Society of America Bulletin, 97(3), 305-323.

^SSaprolite

Saprolite is a deeply weathered rock that retains the original rock’s structure but has been chemically altered to form a soft, friable material. It is significant in understanding weathering processes, soil formation, and the potential for mineral resource exploration.

Reference: Eggleton, R. A. (2001). “The Regolith Glossary: Surficial Geology, Soils, and Landscapes.” CRC LEME.

^SSargasso Sea

The Sargasso Sea is a region of the North Atlantic Ocean characterized by its deep blue water and floating seaweed, primarily Sargassum. It is significant in oceanography for understanding ocean currents, marine ecosystems, and the impacts of climate change on marine environments.

Reference: Nixon, S. W., & Buckley, B. A. (2008). “Sargassum: A Floating Ecological Oasis.” Marine Ecology Progress Series, 364, 279-284.

^SSchistosity

Schistosity is a type of foliation characteristic of schist, where the rock exhibits a planar or layered structure due to the alignment of platy minerals like mica. It is significant in metamorphic petrology for understanding the conditions and processes of regional metamorphism.

Reference: Yardley, B. W. D. (1989). “An Introduction to Metamorphic Petrology.” Longman.

^SSeafloor Spreading

Seafloor spreading is the process by which new oceanic crust is formed at mid-ocean ridges and gradually moves away from the ridge axis. This process is central to the theory of plate tectonics and is important for understanding the dynamics of the Earth’s lithosphere.

Reference: Macdonald, K. C. (1982). “Mid-Ocean Ridges: Fine Scale Tectonic, Volcanic and Hydrothermal Processes within the Plate Boundary Zone.” Annual Review of Earth and Planetary Sciences, 10(1), 155-190.

^SSedimentary Basin

A sedimentary basin is a low-lying area where sediments accumulate over time, often leading to the formation of sedimentary rocks. These basins are significant for understanding geological processes, the history of sedimentation, and the potential for hydrocarbon reservoirs.

Reference: Miall, A. D. (1996). “The Geology of Fluvial Deposits.” Springer.

^SSedimentary Rock

Sedimentary rock is formed by the accumulation and lithification of sediments, which can be derived from the weathering and erosion of pre-existing rocks or from the precipitation of minerals from water. These rocks are significant in geology for preserving fossils, recording past environments, and understanding Earth’s history.

Reference: Boggs, S. (2009). “Petrology of Sedimentary Rocks.” Cambridge University Press.

^SSeismic Hazard

Seismic hazard refers to the potential for earthquake-related ground shaking and damage in a specific area. Assessing seismic hazards is crucial for urban planning, construction practices, and risk management in seismically active regions.

Reference: US Geological Survey (2003). “Earthquake Hazards Reduction Program.” USGS Publications.

^SSeismic Refraction

Seismic refraction is a geophysical method used to measure the velocities of seismic waves traveling through the Earth’s subsurface. This method is important in exploration geophysics for mapping subsurface structures, determining the depth of bedrock, and exploring for natural resources.

Reference: Telford, W. M., Geldart, L. P., & Sheriff, R. E. (1990). “Applied Geophysics.” Cambridge University Press.

^SSeismic Wave

Seismic waves are waves of energy that travel through the Earth, typically generated by earthquakes, volcanic activity, or artificial explosions. They are important in geophysics for understanding the Earth’s internal structure, locating earthquakes, and exploring for natural resources.

Reference: Lay, T., & Wallace, T. C. (1995). “Modern Global Seismology.” Academic Press.

^SSerpentinization

Serpentinization is the process of altering ultramafic rocks, particularly peridotite, into serpentine minerals through hydrothermal activity. This process is significant for understanding plate tectonics, the formation of ophiolites, and the geochemistry of Earth’s mantle.

Reference: Wicks, F. J., & Whittaker, E. J. W. (1977). “Serpentine Textures and Serpentinization.” Canadian Mineralogist, 15(1), 459-488.

^SSill

A sill is a tabular sheet of igneous rock that intrudes parallel to the layering of pre-existing rocks. Sills are significant in understanding the processes of magma emplacement, the thermal effects of intrusions on surrounding rocks, and the structural geology of intrusions.

Reference: Pollard, D. D., & Johnson, A. M. (1973). “Mechanics of Growth of Some Laccolithic Intrusions in the Henry Mountains, Utah, I: Field Observations, Gilbert’s Model, Physical Properties and Flow of the Magma.” Tectonophysics, 18(3-4), 311-354.

^SSiltstone

Siltstone is a fine-grained sedimentary rock composed primarily of silt-sized particles. It is important for understanding sedimentary processes, depositional environments, and the history of sediment transport and accumulation in marine and continental settings.

Reference: Tucker, M. E. (2001). “Sedimentary Petrology: An Introduction to the Origin of Sedimentary Rocks.” Blackwell Science.

^SSinkhole

A sinkhole is a depression or hole in the ground caused by the collapse of a surface layer, often due to the dissolution of underlying carbonate rocks such as limestone. Sinkholes are significant in karst geology for understanding subsurface erosion, groundwater flow, and the hazards associated with land subsidence.

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

^SSolifluction

Solifluction is a type of mass wasting that occurs in periglacial environments, where the slow, downslope flow of water-saturated soil and sediment is driven by freeze-thaw cycles. This process is significant in geomorphology for understanding the dynamics of permafrost regions and the formation of periglacial landscapes.

Reference: French, H. M. (2007). “The Periglacial Environment.” John Wiley & Sons.

^SSphagnum Moss

Sphagnum moss is a type of peat-forming moss commonly found in wetlands, bogs, and fens. This plant is significant for understanding carbon cycling, wetland ecology, and the formation of peat deposits, which play a role in climate regulation.

Reference: Gunnarsson, U. (2005). “Sphagnum and the Ecology of Peatlands.” Ecological Indicators, 5(1), 89-100.

^SSphenophyllum

Sphenophyllum is an extinct genus of primitive vascular plants from the Carboniferous to the Permian periods. This genus is significant for understanding the evolution of land plants and the paleoecology of ancient terrestrial ecosystems.

Reference: Dufrenoy, A. (1837). “Geology of the Carboniferous System.” Annales des Sciences Naturelles.

^SSpheroidal Weathering

Spheroidal weathering is a form of chemical weathering where concentric layers peel off from a rock, typically giving it a rounded shape. This process is significant in geomorphology for understanding the weathering of igneous rocks and the formation of rounded boulders in various landscapes.

Reference: Ollier, C. D. (1984). “Weathering.” Longman.

^SSplay Fault

A splay fault is a subsidiary fault branching off from a main fault, often found in regions of complex tectonic activity. Splay faults are significant in structural geology for understanding the distribution of stress within fault zones and the mechanics of fault networks.

Reference: Sibson, R. H. (1985). “A Note on Fault Re-Activation.” Journal of Structural Geology, 7(5), 751-754.

^SSpreading Center

A spreading center is a tectonic plate boundary where two plates are moving apart, allowing magma to rise and create new oceanic crust. This feature is significant for understanding the processes of seafloor spreading, the formation of mid-ocean ridges, and the dynamics of plate tectonics.

Reference: Müller, R. D., et al. (1997). “The Geodynamics of Oceanic Plateaus.” Geophysical Research Letters, 24(6), 813-816.

Rocks

Glossary

R

Ripple Marks

R

Rock Glacier

R

Rodinia

S

Salt Dome

S

Saprolite

S

Sargasso Sea

S

Schistosity

S

Seafloor Spreading

S

Sedimentary Basin

S

Sedimentary Rock

S

Seismic Hazard

S

Seismic Refraction

S

Seismic Wave

S

Serpentinization

S

Sill

S

Siltstone

S

Sinkhole

S

Solifluction

S

Sphagnum Moss

S

Sphenophyllum

S

Spheroidal Weathering

S

Splay Fault

S

Spreading Center

Galena

RRipple Marks

RRock Glacier

RRodinia

SSalt Dome

SSaprolite

SSargasso Sea

SSchistosity

SSeafloor Spreading

SSedimentary Basin

SSedimentary Rock

SSeismic Hazard

SSeismic Refraction

SSeismic Wave

SSerpentinization

SSill

SSiltstone

SSinkhole

SSolifluction

SSphagnum Moss

SSphenophyllum

SSpheroidal Weathering

SSplay Fault

SSpreading Center

SArchives: Glossary