Sinkholes can form anywhere that the bedrock dissolves away beneath the soil, but classic sinkholes tend to form in limestone, a carbonate rock composed primarily of the minerals calcite (CaCO3), aragonite (CaCO3), and dolomite (CaMg[CO3]2). Worldwide, limestones cover about 15% of land surface. Twenty percent of the US is susceptible to sinkholes. Read more
Easy Science: How sinkholes form
Easy Science: The Great Oxygenation Event
The Earth wasn't always a friendly place to live. Not only was it covered in lava and constantly eruption, its atmosphere was chocked with volcanic gases like carbon dioxide and sulfur dioxide. How and when did the atmosphere reach its current oxygen-rich state? This post will walk through the processes as well as some of the evidence that allows us to understand what happened. While I describe as a series of apparently discrete steps, it's important to remember that these processes sometimes overlapped and that they occurred over a span of time, often millions or billions of years.
Types of volcanic eruptions and their dynamics
This post will focus on the processes driving volcanic eruptions (for more details on all things volcano, visit this awesome site by SDSU). The most important factor controlling eruption type is the composition of the lava, which controls how much gas the lava contains. The more viscous the lava, the more gas it traps—and the more gas, the more explosive the eruption.
Types of volcanic rocks, lava, and deposits
Volcanic rocks are extrusive igneous rocks. There are two main groups: rocks that form from the solidification of lava flows (extrusive), and rocks that form from the compaction of solid volcanic fragments (pyroclastic). This post will cover the basics in easy-to-grasp bullet-point style that facilitates comparison between volcanic rocks. For information on eruption types, click here.
Easy Science: Milankovitch cycles and climate
Milankovitch cycles essentially describe earth's relationship with the sun based on eccentricity, obliquity, and precession. Each of these three components operates on a different timescale, but when they overlap in just the right way, they can reduce insolation (the sunlight hitting the earth) and lower temperatures; conversely, when they work to increase insolation, temperatures go up. For more information on how these cycles influence climate, visit NASA, Skeptical Science, or Wikipedia. Read more →
Easy Science: how oil forms
In the late 1800s, the main use for petroleum was to produce kerosene for heating lamps. Gasoline, a byproduct of this process, was considered a waste; in Pennsylvania, this "waste product" was dumped into the river, where it sometimes caught fire! At the turn of the century, the appearance of the gasoline-powered engine would usher in the "Oil Age", forever changing the world's relationship with "black gold". Modern societies have grown to depend on this millions-years-old substance to function, guzzling over 30 billion barrels a year. Based on estimations of remaining reservoirs, we can keep this rate up through 2050-2150. Walking through the process of how oil forms underscores just how amazing the substance--a fossil from millions of years prior, surviving only be coincidence--really is.
Easy Science: how coal forms
Coal forms when vegetation partially decays in low-oxygen environments, such as swamps. Burial heats and compacts the plant matter, squeezing out water and gases (like methane) while leaving behind carbon. Thus, as the coal increases in rank, its carbon content--and the amount of energy it holds--goes up while its water content goes down.
The coal rank order is: Peat → Lignite (brown coal) → Bituminous coal → Anthracite Read more →
Quick facts about the layers of the Earth
Here is an easy chart gathering together basic facts about each of the earth's layers, from top to bottom: the crust, the mantle, and the core. The crust and uppermost part of the mantle (down to 70 km) from the rigid lithosphere, which contains tectonic plates, underneath which lies the fluid taffy-like asthenosphere, which drives plate motion. Unsurprisingly, as you travel deeper into the earth, things get denser, hotter, and and more pressurized.
Easy Science: how the Appalachian Mountains formed in four steps
The history of the Appalachians spans over a billion years, with four collisions forming the Appalachian Mountains. The last collision occurred around 300 million years ago. Originally, the chain would have rivaled the Himalayas at over 5 km tall, with some mountains perhaps reaching as high as 9 km. Three hundred million years of erosion slowly whittled the mountains away; today, they average 1 km, with the highest point being 2 km at Mount Mitchell, North Carolina. Read more →
Easy Science: cross-section of ocean floor geology
The ocean floor forms at seafloor spreading centers, where basaltic magma pushes out through cracks. This magma ultimately comes from the mantle. What would you see if we could punch out a 8 km deep tube from the sea floor? Unfortunately, that isn't yet possible, but thanks to ophiolites, which are parts of the seafloor that have been uplifted to where we can study them, we have an idea of what it would look like. Read more →