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Expose Nunatak

Nunatak Exposed!

Nunatak Technical Terms

Nunatak: An isolated hill, knob, ridge, or peak of bedrock that projects prominently above the surface of a glacier and is completely surrounded by glacier ice. Compare - inselberg, monadnock. GG


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Remember Nuée Ardent

Nuée Ardent Remembered!

Nuée Ardent Technical Terms

Nuée Ardent: A swiftly flowing, turbulent gaseous cloud, sometimes incandescent, erupted from a volcano and containing ash and other pyroclastics in its lower part; a density current of pyroclastic flow. Compare - lahar. GG


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Discover Novaculite

Novaculite Discovered!

Novaculite Technical Terms

Novaculite: A dense, even-textured, extremely finely grained, siliceous, sedimentary rock recrystallized from chert with microcrystalline quartz dominant over chalcedony (cryptocrystalline quartz). It is hard, white to grayish-black in color, translucent on thin edges, has a dull to waxy luster, and displays smooth conchoidal fracture when broken. Novaculite occurs in the Ouachita Mountains of AR and OK and the Marathon Uplift of TX where it forms erosion resistant ridges. At the Ouachita Mountain type occurrence, novaculite formed by low-grade, thermal metamorphism of bedded chert. This rock serves widely as a whetstone or oilstone. Compare - chert. SW & GG


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Expose Notch

Notch Exposed!

Notch Technical Terms

Notch: A narrow passageway, or short defile between mountains; a deep, close pass. Compare - gap. (b) A breached opening in the rim of a volcanic crater. GG


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Remember Nose Slope

Nose Slope Remembered!

Nose Slope Technical Terms

Nose Slope: A geomorphic component of hills consisting of the projecting end (laterally convex area) of a hillside, resulting in predominantly divergent overland water flow (e.g., sheet wash); contour lines generally form convex curves. Nose slopes are dominated by colluvium and slope wash sediments (e.g., slope alluvium). Slope complexity (downslope shape) can range from simple to complex. Nose slopes are comparatively drier portions of hillslopes and tend to have thinner colluvial sediments and profiles. Compare - head slope, side slope, free face, interfluve, crest, base slope. SW


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Remember Nonsorted Circle

Nonsorted Circle Remembered!

Nonsorted Circle Technical Terms

Nonsorted Circle: A type of patterned ground whose mesh (shape) is dominantly circular and has a nonsorted appearance due to the absence of a boarder of coarse fragments. Vegetation characteristically outlines the pattern by forming a bordering ridge. Diameters commonly range from 0.5 to 3 m. Nonsorted circles include mud boils, earth hummocks, turf hummocks, and frost boils. Nonsorted circles have various origins. Some, such as mud and earth hummocks and frost boils, involve cryoturbation activity and differential heave of frost-susceptible materials. Others, such as mud boils, involve hydraulic pressures and diapir-like displacement of water-saturated sediments. Compare - sorted circle, frost boil, patterned ground. NRC and GG


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Remember Nivation Hollow

Nivation Hollow Remembered!

Nivation Hollow Technical Terms

Nivation Hollow: A shallow, non-cliffed depression or hollow on a mountain side permanently or intermittently occupied by a snow bank or snow patch and produced by nivation. If the snow completely melts each summer the hollow is deepened; otherwise not; may be a cirque precursor if further enlarged and deepened by alpine glaciation. GG