Science Olympiad: Dynamic Planet 2025-2026

Crust

Outermost, solid, rigid.

Mantle

Solid at top, viscous near bottom.

Core

Iron & nickel; outer core liquid, inner core solid.

Lithosphere

crust + upper mantle → divided into tectonic plates.

Convergent

plates collide

Divergent

plates move apart

Transform

plates slide sideways

Continental Crust

granitic, thick, density ~2.7 g/cm³

Oceanic Crust

basaltic, thin, density ~2.9 g/cm³

Ocean-Ocean Divergence

• Rising mantle forms mid-ocean ridge.

• Magma fills fissure → solidifies → plates move apart.

Continent-Continent Divergence

• Thick continental crust → rift valley forms.

• Normal faults develop → central blocks sink.

• Early stage: linear lakes; later: narrow seas → possible new ocean basin.

Ocean-Continent Convergence

Oceanic subducts → trench + volcanoes

Ocean-Ocean Convergence

Both subduct → trench + volcanic island arcs, earthquakes, tsunamis

Continent-Continent Convergence

Plates collide → mountain ranges

Transform Plate Boundries

• Plates slide sideways → no crust formed/destroyed.

• Often found along mid-ocean ridges.

Active Margin

At convergent boundaries → subduction, tectonic activity, narrower, less sediment

Passive Margin

Within plates → wide, low tectonic activity, sediment accumulation

Fringing Reef

Coral forms around volcanic island

Barrier Reef

Island erodes, reef continues → barrier

Atoll Reef

Island disappears → lagoon surrounded by reef

Patch Reef

Small clumps of coral, not connected, circular or rhomboid

Ocean Surface Circulation

Driven by sun → pressure differences → wind → surface currents

West coasts

cold currents from poles

East coasts

warm currents from tropics

Coriolis Effect

Deflects moving water → right (N. Hemisphere), left (S. Hemisphere)

Ekman Spiral

Surface water moves with wind; deeper layers move slower & deflected → net flow 90° from wind → causes upwelling/downwelling

Upwelling

Water rises → nutrient-rich → supports fisheries

Downwelling

Water sinks → oxygen transported downward, nutrients reduced at surface

Surface Convergence

Water moves toward each other → downwelling

Surface Divergence

Water moves apart

Eddies

Circular currents → mix nutrients → support marine life

Thermohaline Circulation

• Driven by density differences (temp + salinity).

• Cold, salty water sinks → flows south → eventually rises (upwelling).

• Circulation is slow → ~1,000–1,200 years per cycle.

Breaking waves

Form when height/wavelength ratio > 1:7

Tides

Caused by gravitational pull of moon & sun

Spring tide

Sun + Moon aligned → strong tides

Neap tide

Sun + Moon perpendicular → weaker tides

El Niño

Weak trade winds → warm water moves east → no upwelling → rain in E. Pacific, drought in W. Pacific

La Niña

Cold water in E. Pacific → opposite effects → stronger Peruvian Current, cooler Pacific

Lithogenous Sediment

Sediment from land

Biogenous Sediment

Sediment from organisms

Hydrogenous Sediment

Sediment precipitated from water

Cosmogenous Sediment

Sediment from space

ADCP

Measures currents

Bushmaster/Chimneymaster

Collect hydrothermal vent fauna

Clod Cards

Measure water flow near organisms

Drifters

Track currents

Satellites

Observe global ocean, land, atmosphere

SPMDs

Monitor organic contaminants

Sonar

Maps depth & objects

Submersibles/Trawls

Collect deep sea organisms, measure biomass

Fronts

Boundaries between air masses → cold, warm, occluded, stationary

Precipitation

Rain, hail, snow depending on latitude

Atmospheric Circulation

Prevailing winds → easterlies (low lat), westerlies (mid lat)

Crest

The highest point of a wave

Trough

The lowest point of a wave

Wave Height

Vertical distance between the crest and the trough

Wavelength (λ)

Horizontal distance between two consecutive crests (or troughs)

Amplitude

Half the wave height (distance from the calm water line to the crest or trough)

Frequency (f)

• Number of waves passing a fixed point per second

• Hertz (Hz) → 1 Hz = 1 wave per second.

Wave Period (T)

Time it takes for two successive crests to pass a point

Wave Speed (c)

How fast the wave travels

• How fast the wave travels

• c=λ/T (wavelength ÷ period)

Wave Steepness

Ratio of wave height to wavelength

Capillary Waves

• Tiny waves caused by surface tension of water.

• Wavelength: <1.7 cm

Ripples

• Small, short waves caused by wind pressure on the water surface.

• Sometimes used interchangeably with capillary waves.

Chop

• Short, irregular waves caused by wind blowing on rough water.

• Makes the ocean surface appear rough and messy.

Swell

• Smooth, long waves that travel far from the storm where they were formed.

• Usually more uniform than chop.

Standing Waves

• Waves that don’t travel forward. They oscillate in place.

• Usually form in enclosed spaces or when waves reflect off an obstruction.