Calabrian (stage) facts for kids

The Calabrian is a specific time period in Earth's history. It is a part of the Pleistocene Epoch. This period lasted from about 1.8 million years ago to 774,000 years ago.

The end of the Calabrian period is marked by a major event. This event was the last time Earth's magnetic poles flipped. This flip happened around 781,000 years ago. It also led to a very cold and dry ice age across the world.

Originally, the Calabrian was a geological stage in Europe. It was mainly defined by the types of mollusk fossils found. Now, it is the second official geological age in the Early Pleistocene. Many mammal groups from the Early Pleistocene first appeared in the time period just before the Calabrian, called the Gelasian. For example, animals like the Platygonus first showed up then.

Understanding the Calabrian Time Period

Scientists divide Earth's long history into different time periods. These periods are like chapters in a book. The Calabrian is one of these chapters. It helps us understand how Earth changed over time.

How Scientists Defined the Calabrian

In the 1800s and early 1900s, scientists studied mollusks (like snails and clams) and Brachiopods. These sea creatures left many fossils. Scientists used these fossils to identify different layers of rock and time. This is called stratigraphy.

The Calabrian was first defined by a group of mollusk fossils. Later, scientists looked for the best rock layers that showed these fossils. By 1948, they started using the first appearance of cool-water sea animals in the Mediterranean Sea as the start of the Calabrian.

Choosing a "Golden Spike" Location

In 1948, a big meeting of geologists decided to place the start of the Pleistocene at the beginning of the Calabrian. They chose a special "type section" in southern Italy. This place would be the official marker.

However, they later found that the original spot was not perfect. The rock layers there were not continuous. So, a new and better spot was chosen. This new location is at Vrica, near Crotone in Calabria, southern Italy.

Scientists used special tests to confirm this new spot. They looked at strontium and oxygen isotopes. They also studied tiny sea creatures called planktonic foraminifera. These tests showed that Vrica was a good place to mark the start of the Calabrian. In 1984, this new "type section" was officially approved. The start date was first thought to be 1.65 million years ago. But new calculations set it at 1.806 million years ago.

The Official Definition of the Calabrian

Today, the official starting point for the Calabrian is called a GSSP. This stands for Global Boundary Stratotype Section and Point. It's like a "golden spike" in the rock layers. The GSSP for the Calabrian is at Vrica, in southern Italy.

Markers for the Start of the Calabrian

The beginning of the Calabrian is defined by several things:

• It starts just after a time when Earth's magnetic field was reversed. This period is known as the Olduvai magnetic chronozone.
• It also starts after the tiny sea plant fossils called Discoaster brouweri disappeared.
• Above this boundary, you start to find tiny sea plants called Gephyrocapsa spp..
• You also find that tiny sea creatures called Globigerinoides extremus are no longer present.

Markers for the End of the Calabrian

The end of the Calabrian period is marked by a very important event. This event is the Brunhes–Matuyama magnetic reversal. This is when Earth's magnetic poles flipped again.

See also

In Spanish: Calabriense para niños