Featured, Geology

Is It Your Fault or Mine?

Today we’re going to talk about various geological formations at Arrowhead Ranch and how they were formed! Below, in the first picture, you are able to see Mount Baldy, a mountain visible from Strawberry Peak. Mount Baldy is part of the San Bernardino mountain range but is in fact on the opposite side of the San Andreas fault. The San Andreas fault is where the Pacific and North American tectonic plates meet and create a transverse boundary. A transverse boundary is where two tectonic plates slide against each other. The motion of two plates sliding against each other can cause earthquakes, which is why California has so many.

san andreas.jpg

In the next picture you are able to see a variety of rocks and minerals that can be found at Arrowhead Ranch. The difference between a rock and a mineral is that rocks are made up of minerals which in turn are made up of elements. One of the most common rocks found at Arrowhead Ranch is granite, which is the most common intrusive igneous rock and also makes up the bulk of the continental crust. An intrusive igneous rock is a rock which cools beneath the earth’s surface. Because it cools beneath the earth’s surface, intrusive igneous rocks have larger crystals, which can often be seen. The granite seen around Arrowhead Ranch often contains three common minerals: mica, quartz, and feldspar. Mica is a flaky and black, quartz is a colorless mineral composed of silica, and feldspar is the one of the most common minerals in the world and can appear either white, pink, red, or even gray. In contrast to intrusive igneous rock such as granite, there are extrusive igneous rocks such as obsidian, a glassy black mineral often found in arrowheads, which cool quickly and hardens without crystals.


Featured, Geology

Ogres, Onions, and the Earth

Ogres, Onions, and the Earth

By: Mars

Ogres, onions, and the Earth are really all one in the same…if you think about it. Ogres and onions have layers just like this very Earth that we live on! You might think that you are standing on a giant pile of rocks, which is probably true, but the below all of those rocks there are even more layers to our magnificent planet.

layersNow let’s start with that pile of rocks we were talking about, geologists (scientists who study the Earth and its processes) call this outermost layer of the the Earth our crust. Just like a pizza, but probably not as tasty and definitely not as cheese! We have two different types of crusts here on Earth: oceanic and continental. Oceanic crust is the layer of rock that sits beneath our big beautiful oceans. This layer is made up of basalt, an igneous rock formed the cooling of lava. Basalt rock is composed mostly of silica, magnesium, and iron. This crust ranges from roughly 3 to 5 miles in thickness. Our continental crust CRUSTon the other hand, is made up mostly of granite, an igneous rock formed from the cooling of magma. Granite rock is composed mostly of silica, aluminum, potassium and calcium. This crust can is made up of valleys and mountains so it can reach thicknesses up to 25 miles! Much like how our pizza crust is broken into different slices, Earth’s crust is broken into pieces we call tectonic plates. We have seven major, large, plates and many minor, small, plates, that pieced together make up the crust of our Earth.

As we continue to peel back the layer of our Earth we make our way to the mantle. Unlike a mantle you might find in your house above your fireplace, this mantle is viscous, meaning it moves around like a thick liquid, maybe even a little jelloy! The viscosity, or jelloyness, of the mantle allows heat to travel in convection currents, just like an oven. Convection currents occur when hotter matter rises, pushing down cooler matter, which is heated and the process continues. Our tectonic plates which rest on top of our mantle move as these currents circulate. Our mantle is composed of silica, magnesium, and iron, similar to the rocks found in our crust. This layer is very important as it makes up 80% of Earth volume and is roughly 1,800 miles thick!

Next we have Earth’s core which, just like an apple core is located in the middle of our Earth. Our core is divided into two parts: the outer core and the inner core. The outer core is made of liquid iron and nickel and is about 1,400 miles thick. While the inner core is composed of solid iron and nickel and has a radius of about 760 miles. The iron in Earth’s core generates 90% of the Earth’s magnetism.

Just like ogres and onions beneath each layer is another one, containing new questions and discoveries. The more layers we peel back the better we are able to understand the Earth we live on!     



Image Sources:

Earth’s layers- https://phys.org/news/2015-12-earth-layers.html

Crusts- https://earthquake.usgs.gov/learn/glossary/?term=crust

Shrek- https://www.roblox.com/library/155651593/Shrek-onion


Weathering and Erosion

Today we’re going to be talking about weathering and erosion and how it can affect the world around us.

Weathering and erosion have helped to shape the world around us in a way that has

radleigh blog grand canyon.png

given us a variety of amazing landmarks such as the Grand Canyon and Niagara falls. The processes of weathering and erosion can often be hard to distinguish between for those not familiar with the two. The most important differences between the two are weather or not the rock in question stays in the same place or not. Weathering is when a rock, boulder, or other geological feature is broken down through either chemical or mechanical means. In this process, the geological feature being affected stays in the same place. Chemical weathering is any sort of chemical change in a rock that causes it to break down. This can be caused by any number of substances from water, which can cause the breakdown of minerals such as limestone through the process of dissolution, to oxygen, which results in the oxidation of minerals such as iron. Mechanical weathering is the physical breaking down of rocks into smaller pieces through a variety of processes. Water is one of the number one causes of mechanical weathering through processes such as crystallization, hydration, and frost action. When either chemical or physical weathering occurs and the sediment from the rocks is transferred to another place, this is known as erosion.

Erosion has helped to shape the landscape around us. In order to remember what processes cause erosion, it is important to remember “the three w’s” of erosion: wind, water, and wear. All three of these processes aid in transferring broken down sediment from one place to another. A great example of how erosion transfers sediment from one place to another is how wind has been able to move sediment from the mountains of San Bernardino all the way down to the beaches of Los Angeles.

Written By: Boo