What is fracture in geography?
A fracture is any separation in a geologic formation, such as a joint or a fault that divides the rock into two or more pieces. A fracture will sometimes form a deep fissure or crevice in the rock.
What is rock jointing?
joint, in geology, a brittle-fracture surface in rocks along which little or no displacement has occurred. Intrusions of molten rock, when cooled, form sills and dikes, which, in many places, show columnar jointing. Three sets of joints perpendicular to the cooling surfaces intersect each other at angles of about 120°.
When can a fracture be considered as a fault?
When rocks break in response to stress, the resulting break is called a fracture. If rocks on one side of the break shift relative to rocks on the other side, then the fracture is a fault.
What are a fracture and a fault within a rock layer?
If tension builds up along a fault and then is suddenly released, the result is an earthquake. Fractures are simply cracks in the crust where there is no movement. Faults are classified according to the direction of relative movement along the fault.
What is Plumose structure?
An unexposed joint surface will reveal an intricate pattern resembling a feather. This feature is refered to as plumose structure and forms on a scale relative to the grain size of a rock. Finer grained rocks will develop finer plumose structure.
What is a responsible for jointing of rocks?
Explanation: Open joints are those in which the blocks have been separated or opened up for small distances in a direction at right angles to the fracture surface. These may be gradually enlarged by weathering processes and develop fissures in the rocks. Hence the joints may be of open or close nature.
What causes jointing?
Formation. Joints arise from brittle fracture of a rock or layer due to tensile stress. This stress may be imposed from outside; for example, by the stretching of layers, the rise of pore fluid pressure, or shrinkage caused by the cooling or desiccation of a rock body or layer whose outside boundaries remained fixed.
What is the difference between a joint and a fault geology?
Joints and faults are types of fractures. A joint is a fracture along which no movement has taken place, usually caused by tensional forces. A fault is a fracture or break in the rock along which movement has taken place. One might expect more earthquakes to occur near faults.
What is gravity’s role in plate tectonics?
The main driving force of plate tectonics is gravity. If a plate with oceanic lithosphere meets another plate, the dense oceanic lithosphere dives beneath the other plate and sinks into the mantle: this process is called subduction.
What is fault in rock?
A fault is a fracture or zone of fractures between two blocks of rock. Faults allow the blocks to move relative to each other. This movement may occur rapidly, in the form of an earthquake – or may occur slowly, in the form of creep. Most faults produce repeated displacements over geologic time.
Apakah kekar merupakan struktur geologi batuan?
KEKAR (JOINT) GEOLOGI STRUKTUR. Salah satu struktur geologi yang dijumpai pada batuan sebagai hasil dari gayagaya yang bekerja pada batuan adalah kekar. Kekar adalah struktur yang dihasilkan dari batuan yang brittle (Hobbs, 1976), dimana batuan relatif belum mengalami dislokasi/pergeseran, hanya peregangan (extension).
Apakah kekar terjadi dalam formasi geologis?
Dalam geologi, kekar adalah pemecahan atau pemisahan dalam formasi geologis, seperti sesar, yang membelah batuan menjadi kepingan-kepingan. Kekar kadang-kadang dapat membentuk retakan yang dalam dan lebar di dalam batuan. Kekar biasanya disebabkan oleh ketidakmampuan batu untuk menahan tekanan yang terlalu besar.
Bagaimana cara terbentuk kekar?
Kekar adalah bidang rekahan yang tidak memperlihatkan pergeseran berarti atau bagian masanya masih saling berhubungan/bergabung. Kekar dapat terbentuk secara primer, seperti kekar kolom dan kekar melembar pada batuan beku maupun secara sekunder, seperti kekar tektonik.