Late Paleozoic icehouse

A long time ago, Earth was very cold.

Big sheets of ice covered the land. This was a very long ice age. It lasted for millions of years.

Plants helped make the world cold. They took gas out of the air. This gas helps keep the world warm. Without it, the air got chilly.

Snow fell and stayed on the ground. The snow grew very deep. It turned into thick ice.

This ice moved across the land. It even moved the rocks.

It was a very different world back then.

A long time ago, Earth went through a very long ice age. This was called the Late Paleozoic icehouse. It lasted from 360 to 255 million years ago.

During this time, giant ice sheets covered much of the land. Most of this ice was on a supercontinent called Gondwana. As the land moved toward the South Pole, the ice grew. The ice sheets moved across Africa, South America, and Australia.

What made the world so cold? One big reason was plants. New types of plants grew on land. These plants took a gas called carbon dioxide out of the air. This gas acts like a blanket to keep Earth warm. When plants took the gas away, the blanket got thin. The air cooled down.

Snow began to stay on the ground during the winter. It grew very deep. The heavy snow turned into thick ice. This ice was so strong it scraped the ground. It left long marks on rocks.

Eventually, the ice age ended. The world became warm again. This change was a big shift for our planet.

The Late Paleozoic icehouse was a very long period of cold weather on Earth. It is also called the Late Paleozoic Ice Age. This ice age lasted from 360 to 255 million years ago. It was the longest ice age during a huge part of Earth's history. During this time, massive ice sheets sat on the surface of the planet.

These ice sheets were not always in the same place. They changed as the land moved around the world. This period is important because it shows how Earth can shift from a cold state to a warm greenhouse state.

Many things worked together to make the world so cold. First, new kinds of plants grew on land. These plants took carbon dioxide out of the air. Carbon dioxide acts like a warm blanket for the planet. As plants took the gas away, the blanket became thin. This caused summers to stay cool. Snow could stay on the ground without melting. Over time, deep snow turned into heavy ice. The movement of continents also played a big part. As the supercontinent Gondwana moved toward the South Pole, the ice grew.

Scientists have studied many clues to learn about this time. They look at rocks and old layers of dirt. In places like Brazil, they found ice layers that were 1400 meters thick. In southern Africa, the Dwyka Formation has ice layers 1000 meters thick.

These layers tell us how much ice once covered the land. In Ethiopia, scientists found marks on rocks left by moving ice. These marks are called striations. They show us exactly where the heavy ice once scraped the ground.

This ice age happened in stages over millions of years. It began in the Late Devonian period. The main part of the ice age started between 335 and 330 million years ago. The ice centers moved across the world as time passed. At first, the ice was in western South America. Later, it moved across Africa. By the end of the ice age, the ice was mostly in Australia. Some parts of the ice age were much more intense than others.

We can see how this old ice age connects to our world today. Just like the ice age, our planet's weather is tied to gases in the air. We know that plants and gases change how warm the Earth feels. The way continents move also changes where ice can grow. Even the way mountains rise can change the weather. Studying the Late Paleozoic icehouse helps us understand how our own home works. It shows us how much the Earth can change over a very long time.

The Late Paleozoic icehouse, often called the Late Paleozoic Ice Age (LPIA), was a massive period of global cooling. It lasted from 360 to 255 million years ago (Mya). This era was the longest-lived ice age during the Phanerozoic eon. During this time, huge ice sheets covered large parts of the Earth's surface. It is a significant period for scientists to study. This is because its end represents the only recorded time Earth shifted from an icehouse state back to a greenhouse state.

Several complex processes worked together to drive this cooling. One major cause was the evolution and spread of land plants. Following the Silurian-Devonian Terrestrial Revolution, vascular plants began to grow extensively on land. These plants performed carbon sequestration, which is the process of capturing and storing carbon. As plants grew, they lowered atmospheric carbon dioxide levels. During the Kasimovian, carbon dioxide may have dropped below 300 parts per million (ppm), reaching as low as 180 ppm. This reduction weakened the greenhouse effect. A thinner greenhouse effect led to cooler summers. These cooler summers meant winter snow did not melt away. Over time, snow accumulated to depths of 6 meters. The weight of this snow eventually converted the lower layers into ice.

Geological changes also played a vital role in the LPIA. The assembly of the supercontinent Pangaea through the Hercynian-Alleghany Orogeny changed the Earth's layout. This movement placed a massive landmass, Gondwana, directly over the South Pole. This positioning allowed ice to grow easily. Additionally, silicate weathering helped remove carbon dioxide from the atmosphere. The closure of the Rheic and Iapetus Oceans also disrupted warm-water currents. This disruption likely contributed to the cooling. Even the rise of mountains helped create alpine glaciers. These glaciers eventually grew and spread into massive continental ice sheets.

The LPIA was not one single event, but a series of stages. Some researchers believe there were up to twenty-five separate ice sheets that grew and shrank independently. These ice centers shifted as Gondwana drifted. At the start, ice was concentrated in western South America. Later, the centers moved eastward across Africa. By the end of the ice age, the ice was mostly in Australia. The LPIA began in earnest between 335 and 330 Mya. The first major glacial period occurred from the Serpukhovian to the Moscovian. This was followed by a warm interglacial interval called the Alykaevo Climatic Optimum. The second major glacial period was the most intense. It occurred from the late Gzhelian across the Carboniferous-Permian boundary. This intense cooling event happened around 300 Ma.

Scientists find evidence of these massive ice sheets in the rock record. In Brazil, the Itararé Group shows ice layers 1400 meters thick. In the Karoo Basin of southern Africa, the Dwyka Formation is 1000 meters thick.

These thick deposits prove how much ice once existed. In Ethiopia, researchers found glacial landforms like striations. Striations are scratches or grooves carved into bedrock by moving ice. Other landforms include roche moutonnées and chatter marks. In Antarctica, the Metschel Tillite contains sediments that preserve evidence of major ice sheets. These geological clues allow us to map the movement and thickness of ancient glaciers.

The LPIA also influenced the global sea level. This is known as glacioeustatic change. As ice sheets grew on land, they pulled water away from the oceans. This caused global sea levels to drop significantly. A major sea level drop was recorded in Idaho during the Bashkirian stage. This drop signaled a major glacial maximum. These changes in sea level are clearly recorded in non-glacial sedimentary basins. They show how the movement of ice on land directly affects the oceans. This connection between ice volume and sea level is a key part of Earth's climate system.

Understanding the LPIA helps us see the connections between biology, geology, and climate. The rise of plants changed the chemistry of the atmosphere. The movement of tectonic plates changed the temperature of the oceans. Even the cycles of the Earth's orbit, known as Milankovitch cycles, influenced the timing of ice growth. These cycles involve changes in the Earth's tilt and orbit. They can drive shorter cycles of warming and cooling within the larger icehouse period. By studying the LPIA, we learn how many different systems must work together to change the entire planet's climate.