Comprehensive Geography Study Notes: Geomorphology, Urban Growth, and Tectonic Hazards

Weathering, Mass Movement, and Geological Processes

Sioncaitheamh (Weathering) is categorized primarily into mechanical and chemical forms. Mechanical weathering (‘MeIchiúil’) includes processes like freeze-thaw (‘gniomh réo-lea’) which occurs frequently on high ground (‘talamh ard’). Chemical weathering (‘Céimiceach’), specifically carbonation, is standard in limestone regions such as the Burren (‘Boireann’) in County Clare (‘Co. Cláir’).

Mass movement, or ‘Oughluiseacht’, involves the movement of material down a slope due to gravity. A fast version of this is the bog burst (‘Bruth portaigh’), which typically happens on high, wet ground (‘talamh ard agus fliuch’). Soil creep (‘Daibhsbreabhadh’) is a very slow type of mass movement occurring on gentle slopes. Landslides (‘Sciorradh talùn’) happen very quickly. The stability of a slope depends on factors like the grade (steep vs. ready/gentle) and moisture levels (dry vs. wet).

Slopes become unstable due to natural or human-driven factors. Human activities include mining (‘mianadóireacht’) and road works (‘obair bóthair’) which may undercut the base of a slope (‘bonn a bhaint ó fhána’). Natural causes include heavy rainfall (‘baisteach trom’), volcanic eruptions (‘bolcán’), or earthquakes (‘crith talaimh’). Vegetation plays a critical role in stabilization; roots (‘Fréamhacha’) help hold the soil together and absorb water through to the soil layers, reducing the impact of erosion from wind and rain.

River Processes and Landforms

A river progresses through three main stages: the Youthful stage (‘Céim na hóige’) characterized by a V-shaped valley (‘V-ghleann’), the Mature stage (‘Céim na haibíochta’ or ‘albhachta’), and the Old Age stage (‘Céim na seanaoise’). Key erosional processes include hydraulic action (‘gniomh hiodrálach’), where the force of water moves and lifts stones, and abrasion (‘Scriobhchaiteamh’), where stones strike against the river bed or banks. Attrition (‘Creimeadh’ or ‘mancaitheamh’) occurs when stones hit each other, becoming smaller and smoother (‘níos lú agus níos réidh’).

A V-shaped valley is formed in the upper course where the river mainly cuts vertically into its bed (‘River cuts into bed’). Weathering then attacks the sides of the valley, causing material to fall into the river to be carried away, leaving the classic steep-sided V-profile.

Coastal Geography and Wave Dynamics

Waves (‘Tonnta’) are movements on the sea's surface caused by the wind. The size and power of a wave depend on the wind's speed and the fetch (‘an ngaoth ag gluaiseacht thar dromchla na farraige’). Waves have two components: the swash (‘BORRUISCE’), which moves up the beach, and the backwash (‘CÙLCHAISE’), which returns toward the sea.

Constructive waves (‘Tonnta thógála’) have a strong swash and a weak backwash (‘borruisce láidir agus cùlchaise lag’), resulting in deposition. Destructive waves (‘Tonnta scriosacha’) occur during poor weather (‘aimsir dhona’) and feature a weak swash and a strong backwash (‘borruisce lag agus cùlchaise láidir’), which erodes the shoreline. Other erosional processes on coasts include compressed air (‘Aer comhbhruite’) forced into rock crevices, attrition from rock strike, and solution (‘tuaslagadh’) where salt chemically dissolves the rock.

Coastal landforms include cliffs (‘Aill’), such as the Cliffs of Moher (‘Aillte an Mhothair’) in County Clare, formed by destructive waves. Other features are Bays and Headlands (‘Bánna agus Rosanna’), formed where soft rock is eroded faster than hard rock. Sea caves (‘Pluais mhara’) can expand into a sea arch (‘Stua mara’) when erosion tunnels through a headland. When the roof of a sea arch collapses, it leaves a coastal pillar known as a sea stack (‘Staca farraige’). A blowhole (‘poll séideáin’) is a passage from the roof of a cave to the surface through which water can be forced during storms.

Longshore drift (‘Srobhadh feadh cladaigh’) occurs when waves transport material along the coast. This leads to depositional landforms like sand spits (‘Goba gainimh’) which grow out from the coast, and tombolos (‘Tombalónna’), which are ridges of sand connecting an island to the mainland. A lagoon or marsh (‘Loch murlach’) may form behind a sand bar or spit. To protect against these forces, humans build sea walls (‘Ballaí mhara’) made of concrete and groynes (‘Gradiacha’) which are low walls built at right angles to the shore to stop longshore drift and accumulate sand.

Geology and Rock Classification

Rocks are classified into three types. Igneous Rocks (‘Bruincarraig’) form from cooled magma or lava; examples include Basalt (‘Basalt’) which is extrusive (‘eishear’) and Granite (‘Gráinchloich’) which is intrusive. Metamorphic Rocks (‘Claochlaithe’) form from heat and pressure; examples include Marble (‘Marmar’) and Quartzite (‘Grianchloich’). Sedimentary Rocks (‘Dríodan’) are made from compressed remains; example includes Limestone (‘Aolchloch’), which often contains fossils (‘iontais’).

Soil types include Brown Earth (‘Ithir donn’), which is deciduous forest soil found in middle altitudes and is rich in humus (‘lán humas’).

Urban Geography: The Growth of Dublin

Dublin (‘Baile Átha Cliath’ or ‘BAC’) has grown significantly due to migration from rural areas and natural birth rates. Following independence in 1923, many people moved from overcrowded city centers to new suburbs. By the 1970s, local governments planned for the expansion of ‘satellite’ towns like Tallaght, Blanchardstown, and Lucan to house the growing population. These towns eventually merged into the wider city footprint.

In the 1990s, the economic boom led to further growth, such as the town of Adamstown near Lucan. However, growth hit challenges like urban decline (‘meath uirbeach’) in older areas and urban sprawl (‘Sraolléail uirbeach’), which is the uncontrolled outward growth of the city onto rural lands. Sprawl causes problems such as a lack of services/amenities and increased traffic congestion due to people living far from the city center.

Case Study: Ballymun Renewal

Ballymun (‘Baile Munna’) serves as a case study for urban change. Initially, high-rise apartments were built without adequate services or nearby jobs, leading to high unemployment, poverty, and social inequality. In 1997, a Master Plan was launched to improve the area. This involved demolishing the old flats and building $5000$ new houses. The project aimed to be sustainable (‘inbhuanaithe’) by reusing the same land and improving community services to ensure a stable population and local jobs.

Distinctions are made between Urban Renewal (‘Athnuachan Uirbeach’), which involves modernizing existing buildings, and Urban Redevelopment (‘Athfhorbairt Uirbeach’), which changes the use of a site (e.g., from old housing to commercial offices). Such projects often target Brownfield sites (‘Láithreáin athfhorbraíochta’). These are preferred over new greenfield sites because infrastructure like water, sewage, and public transport already exists, reducing costs.

Earthquakes and Plate Tectonics

Earthquakes (‘Crith talùn’) occur when tectonic plates (‘Plátaí teictonacha’) collide or rub against each other, building up pressure and friction. When the rock breaks, energy is released from a point underground called the focus (‘Focus’). The point on the surface directly above the focus is the epicenter (‘Epileár’). Energy travels through the earth as seismic waves.

Impacts of earthquakes are measured using a seismograph (‘Seismeagraf’) and the Richter Scale (‘Scála Richter’). Earthquakes measuring $> 7$ on the Richter scale underwater can cause a Tsunami (‘Sunamaí’), where sudden vertical plate movement displaces water, creating waves up to $30\,m$ high that destroy buildings and coastal life. Social impacts include loss of life, injury, and displacement, while economic impacts include infrastructure damage and slow economic growth. Long-term effects include anxiety and homelessness. Examples of major earthquakes include Japan and Haiti.

The Structure of the Earth and Volcanoes

The earth's plates move due to convection currents (‘Sruthanna comhthumadh’) in the mantle (‘mantán’). Heat from the core causes magma to rise to the crust (‘screamh’) where it cools and drags the plates. Volcanoes (‘Bolcán’) form when magma rises through a vent (‘Cráos’) from a magma chamber (‘seomra magma’) under pressure. Examples include Mount Etna in Italy and Mauna Loa in Hawaii, both categorized as active (‘Bolcáin Beo’).

Mid-ocean ridges (‘Droim lár-aigéin’) form where plates pull apart, allowing magma to rise and cool, creating new ocean floor and volcanic mountains. Iceland (‘An Ioslainn’) is a prime example where this activity produces geothermal energy and hot springs. The Pacific Ring of Fire (‘Fáinne tine an Aigéan Ciúin’) contains more than half of the world's active volcanoes because of the frequent collision of tectonic plates in that region.