Bulgaria DZI Geography cheat sheet

Scale is the ratio of map distance to ground distance; a 1:50,000 map means 1 cm on paper equals 500 m on the ground.

Large-scale maps (1:10,000 to 1:200,000) show more detail and cover small areas; small-scale maps (1:1,000,000 and smaller) generalise heavily.

Contour lines connect points of equal elevation; the closer the contours, the steeper the slope, and contours crossing a valley form a V pointing upstream.

Latitude ranges 0°–90° north or south of the equator; longitude ranges 0°–180° east or west of the prime meridian.

A geographic (true) azimuth is measured clockwise from north through 360°; the back azimuth differs by 180°.

Map projections distort shape, area, distance, or direction; conformal projections preserve angles, equal-area projections preserve area.

A map's representative fraction is unitless, so 1:25,000 holds whether distances are measured in cm, m, or km.

Vertical exaggeration equals horizontal scale denominator divided by vertical scale denominator; it shows how many times relief is stretched.

Earth's interior layers by composition: crust, mantle, core; by physical state: lithosphere, asthenosphere, mesosphere, outer core (liquid), inner core (solid).

The lithosphere is the rigid outer shell (crust plus uppermost mantle) broken into tectonic plates that ride on the plastic asthenosphere.

Continental crust is granitic and thick (about 30–70 km); oceanic crust is basaltic, denser, and thin (about 5–10 km).

Igneous rocks form from cooling magma or lava; sedimentary rocks form from compaction and cementation of deposited material; metamorphic rocks form under heat and pressure.

The Mohorovičić discontinuity marks the crust–mantle boundary; the Gutenberg discontinuity separates mantle from core.

Minerals are identified by hardness (Mohs scale 1–10), cleavage, lustre, streak, and crystal form; diamond is 10, talc is 1.

Rock cycles convert among igneous, sedimentary, and metamorphic types through melting, weathering, erosion, burial, and metamorphism.

Divergent boundaries create new crust (mid-ocean ridges, rift valleys); convergent boundaries destroy crust (subduction trenches, fold mountains); transform boundaries slide past each other.

Fold mountains form where compressional forces buckle strata, as in the Alps, Himalayas, and Andes; fault-block mountains form where crust is uplifted or dropped along faults.

Earthquakes occur where stress is released along faults; the focus is the underground origin point, the epicentre is the surface point above it.

Earthquake magnitude (Richter, moment magnitude) measures energy released on a logarithmic scale; intensity (Mercalli) measures observed surface effects.

Volcanoes cluster at subduction zones (explosive, andesitic) and at hot spots or ridges (effusive, basaltic).

Denudation combines weathering, mass movement, erosion, transport, and deposition; agents include water, wind, ice, and gravity.

Karst relief develops where soluble rock (limestone, gypsum) is dissolved, producing caves, sinkholes, poljes, and underground drainage.

Glacial relief features include cirques, arêtes, horns, U-shaped valleys, moraines, and drumlins; fluvial features include meanders, floodplains, and deltas.

The atmosphere layers from bottom up: troposphere (weather, temperature falls with height), stratosphere (ozone layer), mesosphere, thermosphere, exosphere.

Air pressure decreases with altitude; wind blows from high to low pressure, deflected right in the Northern Hemisphere (Coriolis effect) and left in the Southern.

Insolation is strongest at low latitudes because solar rays strike more directly; the equator receives more energy per unit area than the poles.

Climate controls include latitude, altitude, distance from sea, ocean currents, prevailing winds, and relief.

Tropical rainforest climate (Af) has high temperature and rainfall all year; Mediterranean climate (Cs) has dry hot summers and mild wet winters.

A front forms at the boundary of air masses; a cold front brings short heavy precipitation, a warm front brings prolonged gentle precipitation.

Relative humidity is the ratio of actual water vapour to saturation capacity at a given temperature; cooling air raises relative humidity toward 100%.

Water covers about 71% of Earth's surface; about 97% is saline ocean water, and most freshwater is locked in glaciers and ice caps.

The hydrological cycle moves water through evaporation, transpiration, condensation, precipitation, infiltration, runoff, and groundwater flow.

A drainage basin is the area drained by a river and its tributaries; the watershed is the divide separating adjacent basins.

River discharge equals cross-sectional area times average velocity; a hydrograph plots discharge against time after rainfall.

Groundwater accumulates in permeable aquifers between impermeable layers; the water table is the upper surface of saturated rock.

Ocean currents are driven by wind and density differences; warm currents raise coastal temperatures, cold currents lower them and can cause coastal aridity.

Tides result mainly from gravitational pull of the Moon and Sun; spring tides occur at new and full moon, neap tides at quarter phases.

The biosphere is the zone of living organisms, overlapping the lower atmosphere, hydrosphere, and upper lithosphere.

Ecosystem structure includes producers, consumers, decomposers, and abiotic factors; energy flows one way while nutrients cycle.

Food chains transfer energy with roughly a 10% efficiency between trophic levels, so biomass pyramids usually narrow upward.

Photosynthesis converts carbon dioxide and water into glucose and oxygen using light energy; respiration reverses the gas exchange.

Biodiversity hotspots are regions with high species richness and high habitat loss; tropical rainforests and coral reefs are the richest ecosystems.

Biomes are large-scale communities defined by climate: tundra, taiga, temperate forest, grassland, desert, savanna, tropical rainforest.

Human impacts on the biosphere include habitat fragmentation, deforestation, pollution, overexploitation, and invasive species.

Soil horizons from top: O (organic litter), A (humus-rich topsoil), B (accumulation), C (weathered parent material), R (bedrock).

Soil formation factors are parent material, climate, organisms, relief, and time (the CLORPT model).

Podzols form under cool coniferous forest with leaching; chernozems form in temperate grasslands and are humus-rich and fertile.

Laterites form in humid tropics through intense leaching; ferralsols are iron- and aluminium-rich and poor in nutrients.

Saline and alkaline soils develop in arid areas where evaporation exceeds precipitation, drawing salts to the surface.

Alluvial soils form on river floodplains from deposited sediment and are typically fertile and agriculturally valuable.

Natural zones follow climate belts: tundra, taiga, mixed and broadleaf forest, steppe, desert, savanna, tropical rainforest.

Natural increase equals birth rate minus death rate; net migration is immigration minus emigration.

Population growth rate combines natural increase and net migration, usually expressed per 1,000 inhabitants.

The demographic transition has stages: high stationary, early expanding, late expanding, low stationary, and declining.

Population pyramid shapes indicate age structure: broad base means high fertility, narrow base means ageing population.

Total fertility rate is the average number of children per woman; replacement level is about 2.1.

Dependency ratio equals the population under 15 plus over 65 divided by the working-age population, times 100.

Population density equals total population divided by area, usually persons per square kilometre.

Push factors drive migration from a place (conflict, unemployment); pull factors attract migrants (jobs, safety, services).

Site is the actual land a settlement occupies; situation is its position relative to surrounding features such as rivers, routes, and resources.

Rural settlement patterns include dispersed, nucleated, and linear forms, shaped by water, relief, defence, and farming practice.

Urbanisation is the rising share of population living in towns and cities; it accelerates with industrialisation.

Urban land-use models include concentric zones, sector, and multiple nuclei models.

Primacy describes a city disproportionately larger than the second city in a national urban system.

Counter-urbanisation is movement of people from cities to rural areas, often driven by housing cost, congestion, and remote work.

Urban problems include congestion, air pollution, housing shortages, and inadequate infrastructure; solutions include planning, transport, and green space.

Economic sectors: primary (extraction, farming), secondary (manufacturing, construction), tertiary (services), quaternary (knowledge, R&D).

GDP measures the value of goods and services produced within a country; GNI measures income of residents including net income from abroad.

The Human Development Index combines life expectancy, education (mean and expected years), and gross national income per capita.

Industrial location factors include raw materials, energy, transport, labour, market, capital, and government policy.

Agriculture types: subsistence, commercial, intensive, extensive, plantation, and mixed farming.

Trade balance equals exports minus imports; a surplus is positive, a deficit is negative.

Globalisation links economies through trade, investment, transport, and communication, creating global supply chains.

Europe's relief includes the North European Plain, the Hercynian uplands, and the Alpine fold belt; the Atlantic and Mediterranean shape its climates.

Asia contains the highest point on Earth (Mount Everest, 8,849 m) and the lowest land point (Dead Sea shore, about 430 m below sea level).

Africa is crossed by the equator, Prime Meridian, and the Great Rift Valley; the Sahara is the largest hot desert.

North America's major mountain systems are the Rocky Mountains and the Appalachian Mountains; the Great Plains lie between them.

South America's Andes form the longest continental mountain range; the Amazon is the largest river by discharge.

Australia is the flattest and driest inhabited continent, with the Great Dividing Range and vast interior deserts.

Antarctica holds about 90% of Earth's ice and is the coldest, driest, and windiest continent.

Bulgaria lies in southeastern Europe on the Balkan Peninsula, bordered by Romania (Danube), Serbia, North Macedonia, Greece, Turkey, and the Black Sea.

Major relief units: the Danubian Plain in the north, the Balkan Mountains (Stara Planina) across the centre, the Sredna Gora, the Upper Thracian Plain, and the Rila–Pirin–Rhodope massif in the south.

Musala in Rila is the highest peak at 2,925 m; the lowest point is sea level on the Black Sea coast.

The Danube forms most of the northern border; other major rivers include the Maritsa, Iskar, Yantra, and Struma.

Climate is temperate continental, with Mediterranean influence in the southern valleys and along the Black Sea coast.

Bulgaria's Black Sea coast runs from the Romanian border to the Turkish border, with major ports at Varna and Burgas.

Mineral resources include lignite and brown coal, copper ores, lead-zinc ores, and mineral springs; agriculture produces wheat, maize, sunflower, and grapes.