The Highlands: Critical Resources, Treasured Landscapes

Glossary

Glossary anadromous fish: Fish that spawn in freshwater but spend most of their lives in salt water. analogue: Sets of conditions that management seeks to create or maintain. aquifer: An underground layer of water-bearing bedrock or sediments. basal area: The cross-sectional area of a tree measured at chest height. bedrock: All solid rock of the earth’s crust that lies beneath the soil and unconsolidated sediments. braidplains: Networks of shallow channels in which glacial river-plain deposits are laid down. calc-silicates: Metamorphic rocks related to marble but with varying amounts of additional minerals. catadromous fish: Fish that spend most of their lives in freshwater and return to salt water to spawn. chert: Microcrystalline quartz that is deposited in a marine environment under certain chemical conditions. clastic rock: Rocks of sedimentary origin such as sandstone, siltstone, and shale. colluvium: The eroded debris collected at the foot of hillslopes in aprons of rocky sediment. consumptive water uses: Water uses that return some of the used water to the same watershed, with the remainder lost to evaporative or transpiration processes, such as irrigation. crystalline rock: Tough, coarse rock that is generally resistant to weathering. As the rocks formed, individual minerals grew into large crystals that were tightly knitted together. cyanobacteria: Blue-green algae. depletive water uses: Water uses that remove the water entirely from the watershed through the transfer of raw, treated, or used water to another watershed or to coastal waters. downcutting: Erosion by rivers that leads to deepening of valleys. downwarping: The crust of the earth can locally subside to great depths by loading of sediments or plate tectonic interactions. drumlins: A teardrop-shaped elongate hill of glacial sediment formed beneath a glacier. 332 Glossary ductile faults: A fault in which the rock deformed plastically without fracturing. ecoregion: An ecologically and geographically defined area that contains a characteristic assemblage of natural communities, sometimes called a bioregion. ecotone: A transition area between two adjacent ecological communities. eutrophication: Excessive growth of aquatic plant life such as algae and floating plants due to overenrichment of nutrients; often leads to low dissolved oxygen levels as plants decay. evapotranspiration: The loss of water to the atmosphere through a combination of water that evaporates from land and water surfaces, and the water taken up by plant roots and transpired through leaves. fragipan: A dense, firm, water- and root-restrictive horizon formed in the lower subsoil. glaciofluvial: Pertaining to streams fed by melting glaciers, or to the deposits and landforms produced by such meltwater. glaciolacustrine: Features pertaining to glacially formed lakes. gneiss: Banded crystalline metamorphic rock that is highly resistant to weathering and erosion. headwater seeps: Wetland areas where groundwater flows to the surface to become the beginning of streams. hematite: Rock composed of an iron oxide mineral (FeO3) similar to magnetite but red or brown in color and more oxidized. hydric soil: A soil that meets certain technical criteria that demonstrate prolonged periods of anaerobic (low oxygen) conditions. hydrograph: A graph showing changes in water level or discharge over a period of time. hydrologic cycle: The constant movement of water through a watershed. hydrology: The source, flow patterns, depth, and chemistry of water. integrated pest management (IPM): A holistic approach to pest control with the goal of reducing pesticide use by emphasizing alternative means of reducing pest populations. lacustrine fans: Sand and gravel deposits laid down on lake bottoms at the mouths of subglacial tunnel channels. mafic: Dark-colored rock that is rich in iron and magnesium. magnetite: An iron-rich oxide (FeO4) usually found among granitic rocks. metamorphism: The change of a preexisting rock in its minerals and texture as a result of changes in temperature and pressure. metasedimentary gneiss: A gneiss that was a sedimentary rock before undergoing metamorphism. Mesozoic age: Geological age between 245 and 65 million years before the present. migmatites: Mixed rock composed of both igneous and metamorphic rock. molten iron: Liquid iron that can run into a series of molds to produce various iron products, such as tools and munitions. moraine: Mixed sediment that piled at the end of a glacier as it melted. mylonites: Fault rock that has recrystallized into a fine-grained texture and is oriented in linear patterns. Glossary 333 nappes: Rocks that were sheared to such an extent that they folded back over themselves , piling up to form flat-lying sheets and thickening the crust. neotropical migrants: Birds that migrate south each...