Laurentia

Laurentia is a very old part of the Earth.

It is the core of North America. It is also part of Greenland.

Long ago, many small pieces hit each other. These pieces joined to make one big land. This made the land strong and still.

Some rocks here are very, very old. They are much older than you can imagine!

These rocks stay at the surface in Canada.

Sometimes, the land was near the middle of the world. The water was warm and shallow there. Many sea animals lived in the water.

Now, Laurentia is part of our big world. It helps hold our land in place.

Laurentia is the ancient core of North America.

It is a large, stable piece of Earth. This piece includes Greenland. Long ago, Laurentia was a separate continent. It also joined other large land masses called supercontinents.

Laurentia grew through many collisions. It started as six or seven large pieces of crust. These pieces crashed into each other. This built huge mountains. Over time, small islands and other land pieces joined it. This process is called accretion. This helped Laurentia grow much larger.

Some rocks in Laurentia are very old. The Acasta Gneiss is 4.04 billion years old.

In Canada, much of this old rock is at the surface. We call this area the Canadian Shield. Much of the rest of the land is covered by other rocks. These include limestone and sandstone.

At times, Laurentia sat near the equator. This is the middle of the Earth. The water around it was warm and shallow. Many sea animals lived in these waters. Later, Laurentia joined with other lands to form Pangaea.

Laurentia is the ancient geological core of North America.

It is a large, stable piece of Earth called a craton. This craton includes Greenland and parts of what is now Scotland. Many times in history, Laurentia was a separate continent. At other times, it was part of much larger supercontinents. It acts as the solid foundation for the land we live on today.

This continent grew through a long process called accretion. It began when six or seven large pieces of crust collided. These pieces, like the Slave and Superior cratons, crashed together between 2.0 and 1.8 billion years ago. These collisions built huge mountain ranges like the Trans-Hudson belt. Over millions of years, small islands and volcanic arcs also joined the edges. This helped Laurentia double in size.

Scientists have found some of the oldest rocks on Earth here.

The Acasta Gneiss in Canada is 4.04 billion years old. In Greenland, the Istaq Gneiss Complex is 3.8 billion years old. Much of this old rock is visible in the Canadian Shield. In the United States, these rocks are often hidden under layers of sediment. These layers include limestone, sandstone, and shale. These sedimentary rocks were mostly laid down between 650 and 290 million years ago.

Laurentia has moved around the world quite a bit.

It was once part of a supercontinent called Rodinia. Some theories suggest Laurentia sat right on the equator during that time. Later, it became part of another supercontinent named Pannotia. Eventually, Laurentia joined with other lands to form the famous Pangaea. During the Ordovician period, the land was often flooded by shallow, warm seas. These tropical waters were perfect for many sea animals to thrive.

You can think of Laurentia as a giant puzzle that keeps growing. Each piece of the puzzle is a different piece of crust. As these pieces crash together, they stay stuck, making the continent stronger. This is how the solid ground beneath our feet was built. It shows how the Earth is always changing and moving over huge amounts of time.

Laurentia is the ancient geological core of the North American continent. It is a massive continental craton, which is a large and stable block of the Earth's crust. This foundation is much more than just North America. In the past, Laurentia included Greenland and the Hebridean terrane in northwest Scotland. Today, it serves as the solid basement upon which much of the continent rests.

The assembly of Laurentia was a violent and slow process involving many collisions. Between 2.0 and 1.8 billion years ago, the core began to form from six or seven large fragments of Archean crust. The process started when the Slave craton collided with the Rae-Hearne craton. Shortly after, the Rae-Hearne craton collided with the Superior Craton. These large pieces merged with smaller blocks like the Wyoming, Nain, and Superior provinces. These massive collisions created huge mountain ranges, such as the Trans-Hudson orogenic belt. These mountains were likely as large as the modern Himalayas.

Laurentia continued to grow through a process called accretion. Accretion is when new material is added to a growing landmass. For nearly 900 million years, small microcontinents and volcanic island arcs crashed into Laurentia's edges. These pieces were often made of juvenile crust. Juvenile crust is new material formed from fresh magma from the Earth's mantle. Major mountain-building events, or orogenies, helped weld these pieces together. These included the Yavapai orogeny and the Grenville orogeny. The Grenville orogeny, occurring between 1.30 and 0.95 billion years ago, added the Llano-Grenville province to the continent.

Some of the oldest rocks on our planet are found within this structure. In eastern and central Canada, the Canadian Shield exposes much of this ancient rock. The Acasta Gneiss in Canada is 4.04 billion years old. In Greenland, the Istaq Gneiss Complex is 3.8 billion years old. These rocks are often metamorphic or igneous, meaning they were changed by heat or formed from cooling magma. In the United States, these old rocks are often hidden. They are covered by thick layers of sedimentary rocks like limestone, sandstone, and shale. These layers can be over 6,100 meters thick.

Laurentia has been a part of several massive supercontinents throughout Earth's history. One major supercontinent was Rodinia. During the time of Rodinia, Laurentia may have sat directly on the equator. Some scientists believe Laurentia was the core of Rodinia, rotated 90 degrees from its current position. Around 750 million years ago, Rodinia broke apart. Laurentia then briefly joined another supercontinent called Pannotia.

Eventually, Laurentia became an independent continent again, separated from other lands by oceans like the Iapetus Ocean.

During the Ordovician period, Laurentia's environment was very different. The continent was often flooded by shallow, warm, tropical seas. These are known as epicontinental seas, which are seas that cover part of a continent. These waters were not very deep, reaching only about 60 meters at the edges. This warm climate was perfect for sea life. Fossil records of shellfish show that this area was near the equator.

These shallow seas allowed for a massive spike in the number of carbonate shells from marine animals.

As time moved forward, Laurentia continued to merge with other landmasses. By the end of the Silurian, Laurentia fused with Baltica and Avalonia. This new combined landmass was called Laurussia. Later, during the Carboniferous and Permian periods, Laurussia fused with Gondwana. This massive merger created the supercontinent known as Pangaea. This long history of collisions and mergers shows how the solid ground of our modern world was built piece by piece over billions of years.