The oldest known rock on Earth is found along the northeast coast of Hudson Bay, Canada.
Click on image for full size
Courtesy of Jonathan O'Neil
Scientists Discover the Oldest Known Rock on Earth
News story originally written on September 26, 2008
Earth is old, 4.6 billion years old to be exact. But there isn’t much hanging around the planet from those early days. That’s because our planet is a great recycler. Most of the rocks that were formed when Earth was young have been mashed, melted, or eroded into sand as plate tectonic forces move them around. So remnants of Earth’s early crust are extremely rare.
But recently, geologists found rocks from Canada that formed 4.28 billion years ago. That’s 250 million years older than any other known rocks. They used a new instrument called a thermal ionization mass spectrometer to learn about the rocks’ age and geochemistry. By measuring the small amounts of two rare earth elements in the rocks, the geologists could measure the age of the rocks. Some of the rock samples were as young as 3.8 billion years old. Others were as much as 4.28 billion years old. These oldest rocks may have formed from ancient volcanoes.
These rocks come from an area on the eastern shore of Hudson Bay in northern Quebec called the Nuvvuagittuq greenstone belt. Scientists have known for several years that the rocks in this area were very old. Now we know how old.
Individual mineral grains called zircons are still the oldest part of the Earth’s geosphere. Zircon grains, which come from Western Australia, are 4.36 billion years. Before this study, the oldest dated whole rocks were from Canada’s Northwest Territories, which are 4.03 billion years old.
Last modified September 26, 2008 by Lisa Gardiner.
Shop Windows to the Universe Science Store!
Our online store
on science education, classroom activities in The Earth Scientist
specimens, and educational games
You might also be interested in:
The main force that shapes our planet's surface over long amounts of time is the movement of Earth's outer layer by the process of plate tectonics. This picture shows how the rigid outer layer of the Earth,...more
Even though there are 92 elements that are naturally found, only eight of them are common in the rocks that make up the Earth’s outer layer, the crust. Together, these 8 elements make up more than 98%...more
Scientists have learned that Mount Hood, Oregon's tallest mountain, has erupted in the past due to the mixing of two different types of magma. "The data will help give us a better road map to what a future...more
The Earth's mantle is a rocky, solid shell that is between the Earth's crust and the outer core, and makes up about 84 percent of the Earth's volume. The mantle is made up of many distinct portions or...more
Some geologic faults that appear strong and stable, slip and slide like weak faults, causing earthquakes. Scientists have been looking at one of these faults in a new way to figure out why. In theory,...more
The sun goes through cycles that last approximately 11 years. These solar cycle include phases with more magnetic activity, sunspots, and solar flares. They also include phases with less activity. The...more
Studying tree rings doesn't only tell us the age of that tree. Tree rings also show what climate was like for each year of a tree's life, which means they can tell us about climates of the past and about...more