Question

Make an events-chain concept map that describes seafloor spreading along a divergent plate boundary. Choose from the following phrases: magma cools to form new seafloor, convection currents circulate hot material along divergent boundary, and older seafloor is forced apart.

Short answer

Seafloor spreading involves convection currents circulating, magma cooling to form new seafloor, and older seafloor being forced apart.

Step-by-step solution

Understand Seafloor Spreading Basics

Seafloor spreading occurs at divergent plate boundaries where tectonic plates move apart. This process results in the formation of new oceanic crust as magma rises to the surface.

Identify Key Phrases

The key phrases provided are: 'magma cools to form new seafloor,' 'convection currents circulate hot material along divergent boundary,' and 'older seafloor is forced apart.' These will be used to create the event-chain.

Start with Convection Currents

First, 'convection currents circulate hot material along divergent boundary' initiates the process. Hot magma is pushed upwards due to these currents at the mid-ocean ridge (the divergent boundary).

Observe Magma at the Surface

Next, 'magma cools to form new seafloor.' As the magma reaches the surface at the mid-ocean ridge, it cools and solidifies, creating new oceanic crust.

Result in Seafloor Spreading

Finally, 'older seafloor is forced apart.' The formation of new crust causes the older seafloor to spread apart, moving away from the ridge.

Create the Events-chain Map

Connect the events in sequence: 1. Convection currents circulate hot material. 2. Magma cools to form new seafloor. 3. Older seafloor is forced apart. This completes the conceptual map of seafloor spreading.

Key concepts

Divergent Plate Boundary

A divergent plate boundary is a region where two tectonic plates are moving away from each other. This movement occurs because of the forces within the Earth's mantle that drive them apart. At divergent boundaries, you'll often find geological features like mid-ocean ridges due to this movement. These areas are crucial for the creation of new crust on our planet.
As the plates separate, magma from the mantle rises to fill the gap. This activity is not only vital for seafloor spreading but also contributes to the dynamic and ever-changing nature of the Earth's surface. Over time, new crust forms from the cooled magma, making divergent boundaries essential for understanding how our ocean floors expand and change.

Convection Currents

Convection currents are the driving force behind the movement of tectonic plates. Located in the Earth's mantle, these currents circulate because of the heat from the Earth's core. Hotter, less dense material rises toward the Earth's surface, while cooler, denser material sinks back down. This creates a cycle that constantly moves the Earth's mantle and the plates above it.
These currents are crucial in maintaining the cycle of seafloor spreading at divergent boundaries. As the hot mantle material rises, it pushes the tectonic plates apart, allowing magma to ascend to the surface and form new oceanic crust. Understanding convection currents is essential for grasping how large-scale geological processes, like seafloor spreading, function.

New Oceanic Crust

The formation of new oceanic crust is a critical component of seafloor spreading. When tectonic plates diverge at a boundary, magma rises from the mantle to fill the space created by this movement. Upon reaching the cooler temperatures near the Earth's surface, the magma solidifies, forming basalt, which is the primary rock type of new oceanic crust.
This process is ongoing and continuous, causing the seafloor to expand over time. Interestingly, the age of oceanic crust increases as you move away from a mid-ocean ridge, with the youngest crust located closest to the ridge itself. This pattern provides valuable insight into the history and dynamics of the Earth’s surface.

Mid-Ocean Ridge

Mid-ocean ridges are underwater mountain ranges formed by the seafloor spreading at divergent plate boundaries. Spanning across the world's oceans, these ridges represent the most extensive chain of mountains on Earth, although most are submerged beneath the sea.
As magma rises due to convection currents, it emerges at these ridges, creating new oceanic crust. Over time, the ocean floor gradually spreads away from the ridge, carrying older crust with it. This continuous cycle of creation and movement is central to the dynamic restructuring of the oceanic plates. Understanding mid-ocean ridges is vital for students to grasp the ongoing geological processes shaping our planet.