Columnar jointed basalt in Turkey

Columnar jointing in the basalt of the Giant's Causeway in Ireland

A joint is a generally planar fracture formed in a rock as a result of extensional stress. Joints are distinct from faults because joints do not have any significant offset of strata either vertically or horizontally.So joint is the plane where two blocks have a least displacement. Image File history File links Download high resolution version (2304x1728, 1708 KB)Basalt Columns in Boyabat Province, Sinop, Turkey (Black Sea Region). ... Image File history File links Download high resolution version (2304x1728, 1708 KB)Basalt Columns in Boyabat Province, Sinop, Turkey (Black Sea Region). ... Image File history File linksMetadata Download high resolution version (1024x768, 282 KB) Summary Hexagonal basaltic stones at the Giants Causeway in Nothern Ireland co. ... Image File history File linksMetadata Download high resolution version (1024x768, 282 KB) Summary Hexagonal basaltic stones at the Giants Causeway in Nothern Ireland co. ... Basalt columns The Giants Causeway is an area of 40,000 tightly packed basalt columns resulting from a volcanic eruption 60 million years ago. ... A fracture is any discontinuous plane in a geologic formation, such as bedding planes, joints, faults or stylolites. ... Fault in metamorphosed strata near Adelaide, Australia Geologic faults or simply faults are planar rock fractures which show evidence of relative movement. ... Goldenville Strata exposed at a quarry in Bedford, Canada. ...

Joints form in solid, hard rock when a rock is stretched past its elastic modulus. When this happens the rock fractures, in a plane perpendicular to the extensional stress (the direction of finite stretch) and parallel with the minimum compressive stress, which is usually vertical (eg. the atmosphere above a column of rock, with a horizontal ground surface). ...

Joints are typically formed due to erosion of the overlying strata exposed at the surface. This removal of overlying rock results in extensional stresses and the fracturing of underlying rock. Joints can also form via cooling of hot rock masses, particularly lava, which form cooling joints, the underlying structure of columnar jointing or columnar basalts. Look up lava, Aa, pahoehoe in Wiktionary, the free dictionary. ... Basalt Basalt is a common gray to black volcanic rock. ...

Measurement of joint patterns can be useful in characterising the tectonic history of extension through an area because of this relationship between the direction of finite stretch and the minimum compressive stress. Joint propagation directions can also be analyzed by characterising plumose structures on the faces of joints, which manifest as fan-shaped irregularities which originate at the point of rupture and propagate toward the site of minimum compressive stress.