In geology, a blowhole or marine geyser is formed as sea caves grow landward and upward into vertical shafts and expose themselves toward the surface, which can result in hydraulic compression of seawater that is released through a port from the top of the blowhole. [1] The geometry of the cave and blowhole along with tide levels and swell conditions determine the height of the spray. [2] [3]
Blowholes are likely to occur in areas where there are crevices, such as lava tubes, in rock along the coast. [4] These areas are often located along fault lines and on islands. [4] As powerful waves hit the coast, water rushes into these crevices and bursts out in a high pressured release. [4] It is often accompanied by a loud noise and wide spray, and for this reason, blowholes are often sites of tourism. [4]
Marine erosion on rocky coastlines produce blowholes that are found throughout the world. They are found at intersecting faults and on the windward sides of a coastline where they receive higher wave energy from the open ocean. [5] The development of a blowhole is linked to the formation of a littoral cave. These two elements make up the blowhole system. A blowhole system always contains three main features: a catchment entrance, a compression cavern and an expelling port. The arrangement, angle and size of these three features determine the force of the air to water ratio that is ejected from the port. [6] The blowhole feature tends to occur in the most distal section of a littoral cave. As their name suggests, blowholes have the ability to move air rapidly. Strong reverse draughts in response to pressure changes in a connecting littoral cave can send wind speeds upwards of 70 km/h. [7]
The formation of a blowhole system begins as a littoral cave is formed. The main factors that contribute to littoral caves formation are wave dynamics and the parent material’s rock property. A parent material property such as susceptibility or resistance to weathering plays a major role in the development of caves. Littoral caves can be formed by one of two processes: caves made of limestone are produced by karst (dissolution) processes, and caves made of igneous rock are produced by pseudokarst (non-dissolutional) processes. [8] In time the littoral cave enlarges growing inland and vertically through weak joints in the parent material. As weathering continues the roof of the cave is exposed, and the blowhole continues to enlarge, eventually the roof of the littoral cave is weaken and collapses. This creates a steep-wall inlet that allows the next stage of coastal morphology to progress. [9]
La Bufadora is a large example of a blowhole located in the Punta Banda Peninsula of Baja California, Mexico. It consists of a littoral cave with a thin opening that has a recurrence eruption interval of 13 -17 seconds, ejecting water up to 100 ft. above sea level. [10]
Blowholes have the capacity to change the topography near their locations. Blowholes can eventually erode the area surrounding the crevices to form larger sea caves. [11] In some instances, the cave itself may collapse. [11] This event may create shallow pools along the coast. [12]
A blowhole is also the name of a rare geologic feature in which air is blown through a small hole at the surface due to pressure differences between a closed underground system and the surface. The blowholes of Wupatki National Monument are an example of such a phenomenon. It is estimated that the closed underground passages have a volume of at least seven billion cubic feet. Wind speeds can approach 30 miles per hour. [2] Another well-known example of this kind of blowhole is the natural entrance to Wind Cave in South Dakota. [13]
The coast, also known as the coastline, shoreline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. Shores are influenced by the topography of the surrounding landscape, as well as by water induced erosion, such as waves. The geological composition of rock and soil dictates the type of shore which is created. The Earth has around 620,000 kilometres (390,000 mi) of coastline. Coasts are important zones in natural ecosystems, often home to a wide range of biodiversity. On land, they harbor important ecosystems such as freshwater or estuarine wetlands, which are important for bird populations and other terrestrial animals. In wave-protected areas they harbor saltmarshes, mangroves or seagrasses, all of which can provide nursery habitat for finfish, shellfish, and other aquatic species. Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessile animals and various kinds of seaweeds. In physical oceanography, a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of the shore, representing the intertidal zone where there is one. Along tropical coasts with clear, nutrient-poor water, coral reefs can often be found between depths of 1–50 meters.
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes, with little or no vegetation, are called ergs or sand seas. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the stoss (upflow) side, where the sand is pushed up the dune, and have a shorter slip face in the lee side. The valley or trough between dunes is called a dune slack.
Erosion is the action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as physical or mechanical erosion; this contrasts with chemical erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres.
Karst is a topography formed from the dissolution of soluble carbonate rocks such as limestone, dolomite, and gypsum. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. More weathering-resistant rocks, such as quartzite, can also occur, given the right conditions.
Geomorphology is the scientific study of the origin and evolution of topographic and bathymetric features generated by physical, chemical or biological processes operating at or near Earth's surface. Geomorphologists seek to understand why landscapes look the way they do, to understand landform and terrain history and dynamics and to predict changes through a combination of field observations, physical experiments and numerical modeling. Geomorphologists work within disciplines such as physical geography, geology, geodesy, engineering geology, archaeology, climatology, and geotechnical engineering. This broad base of interests contributes to many research styles and interests within the field.
A landform is a natural or anthropogenic land feature on the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography. Landforms include hills, mountains, canyons, and valleys, as well as shoreline features such as bays, peninsulas, and seas, including submerged features such as mid-ocean ridges, volcanoes, and the great ocean basins.
A stack or sea stack is a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast, formed by wave erosion. Stacks are formed over time by wind and water, processes of coastal geomorphology. They are formed when part of a headland is eroded by hydraulic action, which is the force of the sea or water crashing against the rock. The force of the water weakens cracks in the headland, causing them to later collapse, forming free-standing stacks and even a small island. Without the constant presence of water, stacks also form when a natural arch collapses under gravity, due to sub-aerial processes like wind erosion. Erosion causes the arch to collapse, leaving the pillar of hard rock standing away from the coast—the stack. Eventually, erosion will cause the stack to collapse, leaving a stump. Stacks can provide important nesting locations for seabirds, and many are popular for rock climbing.
Landforms are categorized by characteristic physical attributes such as their creating process, shape, elevation, slope, orientation, rock exposure, and soil type.
A spit or sandspit is a deposition bar or beach landform off coasts or lake shores. It develops in places where re-entrance occurs, such as at a cove's headlands, by the process of longshore drift by longshore currents. The drift occurs due to waves meeting the beach at an oblique angle, moving sediment down the beach in a zigzag pattern. This is complemented by longshore currents, which further transport sediment through the water alongside the beach. These currents are caused by the same waves that cause the drift.
The Wupatki National Monument is a United States National Monument located in north-central Arizona, near Flagstaff. Rich in Native American archaeological sites, the monument is administered by the National Park Service in close conjunction with the nearby Sunset Crater Volcano National Monument. Wupatki was established as a national monument in 1924 and was listed on the National Register of Historic Places on October 15, 1966. The listing included three contributing buildings and 29 contributing structures on 35,422 acres (14,335 ha).
La Bufadora is a blowhole and tourist attraction located on the Punta Banda Peninsula in Baja California, Mexico, about 17 miles south of Ensenada.
Glaciokarst is a geological term that refers to a specific type of karst landscape that been influenced significantly by past glacial activity.
Biogeomorphology and ecogeomorphology are the study of interactions between organisms and the development of landforms, and are thus fields of study within geomorphology and ichnology. Organisms affect geomorphic processes in a variety of ways. For example, trees can reduce landslide potential where their roots penetrate to underlying rock, plants and their litter inhibit soil erosion, biochemicals produced by plants accelerate the chemical weathering of bedrock and regolith, and marine animals cause the bioerosion of coral. The study of the interactions between marine biota and coastal landform processes is called coastal biogeomorphology.
A sea cave, also known as a littoral cave, is a type of cave formed primarily by the wave action of the sea. The primary process involved is erosion. Sea caves are found throughout the world, actively forming along present coastlines and as relict sea caves on former coastlines. Some of the largest wave-cut caves in the world are found on the coast of Norway, but are now 100 feet or more above present sea level. These would still be classified as littoral caves. By contrast, in places like Thailand's Phang Nga Bay, solutionally formed caves in limestone have been flooded by the rising sea and are now subject to littoral erosion, representing a new phase of their enlargement.
Coastal engineering is a branch of civil engineering concerned with the specific demands posed by constructing at or near the coast, as well as the development of the coast itself.
Marjorie Mary Sweeting, was a British geomorphologist specializing in karst phenomena. Sweeting had gained extensive knowledge on various topographies and landscapes by travelling around the world to places such as Greece, Australia, Czechoslovakia, United States, Canada, South Africa, Belize, and most notably China. She published Karst Landforms, and Karst in China: its Geomorphology and Environment. The latter is the first comprehensive Western account of China's karst, and one of the first western published works on the karst found within China, despite being a male dominated field.
A solutional cave, solution cave, or karst cave is a cave usually formed in the soluble rock limestone. It is the most frequently occurring type of cave. It can also form in other rocks, including chalk, dolomite, marble, salt beds, and gypsum.
The Danxia landform refers to various landscapes found in southeast, southwest and northwest China that "consist of a red bed characterized by steep cliffs". It is a unique type of petrographic geomorphology found in China. Danxia landform is formed from red-coloured sandstones and conglomerates of largely Cretaceous age. The landforms look very much like karst topography that forms in areas underlain by limestones, but since the rocks that form danxia are sandstones and conglomerates, they have been called "pseudo-karst" landforms. They were formed by endogenous forces and exogenous forces.
The Pancake Rocks and Blowholes are a coastal rock formation at Punakaiki on the West Coast of the South Island of New Zealand. They are a popular visitor attraction.
