Fast vs Slow Earth Changes Explorer

Fast changes happen in seconds to days and are easy to witness:

• Earthquakes shake and crack the ground in seconds
• Landslides move rocks and soil down a hill in minutes
• Flash floods reshape riverbanks in hours
• Tsunamis flood coastlines within hours of an earthquake
• Volcanic eruptions build new land in hours to days

Slow changes take years to millions of years but leave lasting landforms:

• Glacier retreat reshapes valleys over decades to centuries
• River erosion widens valleys over thousands of years
• Soil formation builds rich soil over hundreds of years
• Canyon formation carves deep rock over millions of years
• Continental drift moves continents over millions of years

We know slow changes happened even though nobody watched them. Geologists read clues left in the landscape:

• Rock layers in canyon walls record millions of years of history
• U-shaped valleys show where glaciers once carved through mountains
• Matching fossils on different continents prove the lands were once joined
• Rounded pebbles in riverbeds show water wore down sharp edges over time

Earth is about 4.5 billion years old. Processes that seem very slow to us are actually fast compared to Earth's full history:

• The Grand Canyon formed over about 5 to 6 million years
• The Himalayas are still growing a few millimeters each year
• North America and Europe drift apart about 2.5 cm per year
• A mountain range can rise and erode away completely over millions of years