Earth’s Crust Overview
The Earth's crust is the outermost layer, comprising less than 1% of the planet's volume. Despite its thinness, it's where all known life exists, and it contains many of the minerals we use.
Crust Types: Oceanic vs Continental
The crust varies significantly beneath oceans and continents. Oceanic crust is denser and thinner (~7 km) than continental (~35 km), mostly basaltic, while continental crust is composed mainly of less dense granite.
Elemental Abundance
Oxygen is the most abundant element in the crust, accounting for 46.6% by weight. Silicon follows at 27.7%, making silica-based minerals common. Aluminium, iron, calcium, sodium, potassium, and magnesium are also significant.
Unique Mineral Formation
The crust holds over 4,000 minerals, but many are rare. For instance, diamonds form under high-pressure conditions in the mantle, only reaching the crust via volcanic pipes called kimberlites.
Crustal Recycling
Plate tectonics recycles the crust through subduction, where oceanic plates dive beneath continental plates, melting into the mantle and potentially resurfacing as volcanic material.
Soil: Crust's Organic Layer
Soil is the crust's living top layer, formed from weathered rock and organic matter over thousands of years. It's crucial for agriculture and supports Earth's ecosystems.
Crustal Evolution
The Earth's crust has evolved for over 4 billion years. The oldest continental crust rock dates back about 4 billion years, providing clues to early Earth conditions and continental formation processes.Ancient Crust's Moon Connection
Some of Earth's oldest crust found in Australia contains minerals older than the Moon, dating back over 4.4 billion years!
What percent of Earth's volume is crust?
Less than 1%
About 5%
Over 10%
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