Cinder cones, lava domes, and shield volcanoes are all extrusive landforms formed by the accumulation of lava flows. However, one notable exception to this group is calderas, which are formed by the collapse of a volcano’s summit following a large eruption.
Delving into the World of Intrusive Landforms: Dikes
Welcome, fellow earth enthusiasts! Today, we’re going to take a closer look at a fascinating type of landform that’s been hiding in plain sight all along: dikes!
What’s Up with Dikes?
Picture this: you’ve got some nice, molten rock deep down in the earth’s crust. It’s all cozy and warm, just minding its own business. But then, something happens. The pressure builds up, and the molten rock has no choice but to find a way out. It decides to take a sneaky path, squeezing its way through cracks and weaknesses in the surrounding rock. And voila! That’s how dikes are born.
These narrow, vertical sheets of igneous rock can range in thickness from a few inches to hundreds of feet. They’re often found running parallel to each other, like a bunch of nature’s zippers.
How Dikes Get Their Groove On
Dikes form when magma (molten rock) intrudes into existing rock formations. As the magma cools and solidifies, it fills the cracks and gaps, creating a dike. The type of rock that forms in the dike depends on the composition of the magma.
Characteristics of a Dike
Dikes have some telltale characteristics that make them easy to spot. They’re usually dark in color, thanks to the presence of minerals like magnetite. They also tend to have sharp, well-defined edges, and they often intersect with other dikes at right angles.
So, there you have it, folks! Dikes are a fascinating example of how the earth’s internal forces can shape the landscape above. They’re a testament to the power of nature, and a reminder that even the most solid-looking ground can have its secrets hidden beneath the surface.
Extrusive Landforms: Sculpted by Volcanic Eruption
Calderas: Titans of Volcanic Descent
Imagine a massive volcanic crater, so vast that it could swallow an entire city. That’s a caldera, the legacy of a colossal volcanic eruption that literally blows the top off a mountain. These behemoths are formed when a volcano’s magma chamber empties, causing the overlying rock to collapse, creating a breathtaking depression that can stretch for miles.
Cinder Cones: Tiny but Mighty
Picture a heap of cinder blocks piled up haphazardly. Cinder cones, the pint-sized cousins of volcanoes, are built from fragments of lava called cinders. These sprightly youngsters are often found near larger volcanoes and are formed when lava fountaining erupts from the ground, spewing out smaller bits of rock that accumulate around the vent.
Lava Flows: Smooth and Deadly
Think of a river, but replace the water with molten rock. That’s a lava flow, a stream of lava that pours out of a volcano during an eruption. These fiery rivers can stretch for kilometers, burning and consuming everything in their path. Lava flows vary in their speed and thickness, creating different formations such as smooth-surfaced pahoehoe or rugged aa flows.
Lava Domes: Slow and Steamy
Imagine a blob of viscous lava that stubbornly refuses to budge. Lava domes are formed when thick, sticky lava oozes out of a volcanic vent and piles up, creating a rounded, dome-shaped structure. These lava domes can be quite impressive in size, and their slow movement allows them to develop intricate patterns and textures.
Well there you have it, folks! All of the aforementioned landforms are extrusive, with the exception of one. Can you guess which one it is? If you’re still stumped, don’t fret – we’ll be exploring this topic further in an upcoming article. So, stay tuned! In the meantime, thanks for sticking around and reading my ramblings. I appreciate you taking the time to visit, and I hope you’ll come back again soon for more earth science adventures.