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Paraná, river, Brazil, Paraguay, and Argentina

(Encyclopedia)Paraná, river, c.2,000 mi (3,200 km) long, formed by the junction of the Paranaíba and the Rio Grande, SE Brazil. It has the second largest drainage system in South America. It flows generally south...

Negro, Río, river, Uruguay and Brazil

(Encyclopedia)Negro, Río rēˈō nāˈgrō [key], principal river of Uruguay, c.500 mi (800 km) long, rising in S Brazil and flowing SW across central Uruguay to the Uruguay River. It traverses a sheep-raising reg...

Blackstone River Valley National Historical Park

(Encyclopedia)Blackstone River Valley National Historical Park: see National Parks and Monuments (table). ...

Upper Delaware Scenic and Recreational River

(Encyclopedia)Upper Delaware Scenic and Recreational River: see National Parks and Monuments (table)national parks and monuments (table). ...

Upper Missouri River Breaks National Monument

(Encyclopedia)Upper Missouri River Breaks National Monument: see National Parks and Monuments (table)national parks and monuments (table). ...

cuesta

(Encyclopedia)cuesta kwĕsˈtə [key], asymmetric ridge characterized by a short, steep escarpment on one side, and a long, gentle slope on the other. The steep side exposes the edge of erosion-resistant rock layer...

chrysoberyl

(Encyclopedia)chrysoberyl krĭsˈəbĕrˌĭl [key] [Gr.,=golden beryl], a beryllium aluminate used as a gem. It has a vitreous luster and is transparent to translucent. The more valuable cat's-eye is a variety of c...

olivine

(Encyclopedia)olivine ŏlĭvˈēn [key], an iron-magnesium silicate mineral, (Mg,Fe)2SiO4, crystallizing in the orthorhombic system. It is a common constituent of magnesium-rich, silica-poor igneous rocks; metamorp...

garnet

(Encyclopedia)garnet, name applied to a group of isomorphic minerals crystallizing in the cubic system. They are used chiefly as gems and as abrasives (as in garnet paper). The garnets are double silicates; one of ...

Equisetophyta

(Encyclopedia)Equisetophyta ĕkˌwəsətŏfˈətə [key], small division of the plant kingdom consisting of the plants commonly called horsetails and scouring rushes. Equisetum, the only living genus in this divisi...