What’s the story of the shear face in the new Mac OS Catalina wallpaper?

The Story Behind That Awesome Catalina Wallpaper: It’s More Than Just a Pretty Picture

Remember that stunning wallpaper that came with macOS Catalina? The one with the rugged coastline and that striking diagonal line? Turns out, that “shear face,” as it’s often called, has a pretty cool story to tell. It’s not just some random rock formation; it’s a window into millions of years of geological history on Santa Catalina Island, just off the coast of Southern California.

So, what’s the deal with that diagonal line? Well, despite the name, it’s not actually a “shear” in the way geologists usually use the term for faults. Instead, it’s what’s known as a bedding plane. Think of it like this: imagine stacking pancakes one on top of the other. Each pancake is a layer of sediment that, over time, turned into rock. The surface between each pancake? That’s a bedding plane.

Now, picture those pancake layers (or rock layers, in this case) originally lying flat. Over eons, the Earth’s forces got to work, tilting and lifting those layers. The Catalina wallpaper shows exactly that: a tilted bedding plane. The rock layers that used to sit on top of that diagonal surface have been worn away by the relentless power of wind and waves, revealing the ancient surface beneath. It’s a classic case of what happens when you give geology enough time!

Catalina Island itself is a geological wonderland. It’s part of a larger region called the California Continental Borderland, which is basically a jumble of faults and tectonic activity. The island boasts all sorts of interesting rocks, including the Catalina Schist. This isn’t your average rock; it was formed deep inside the Earth under intense pressure and heat.

What’s really wild about the Catalina Schist is that it has what’s called an inverted metamorphic gradient. In simple terms, the rocks that formed at higher temperatures are found above the rocks that formed at lower temperatures. It’s like nature turned things upside down! Geologists believe this happened because of complex processes like subduction, where one tectonic plate slides beneath another. The island also has some igneous rock (quartz diorite) and a sedimentary rock called the San Onofre Breccia, which is made up of bits and pieces of the Catalina Schist and volcanic rocks. It’s like a geological mixed salad!

But the island’s story isn’t just about natural forces. Humans have played a role too. The native Tongva people used to quarry soapstone on the island to make bowls and tools. These quarries are some of the oldest historical sites on Catalina. Later on, in the late 1800s and early 1900s, there was a mining boom as people searched for silver and other minerals. The island’s rock was even used to build the breakwater at San Pedro harbor. Talk about putting the local geology to good use!

Capturing that iconic wallpaper shot wasn’t a walk in the park, either. Apple didn’t just stumble upon it. A team of photographers and videographers had to hike across the island and use a drone to get the right angle. It shows you how remote and special that location really is.

So, next time you see that macOS Catalina wallpaper, remember it’s more than just a pretty picture. It’s a story of geological forces, ancient rocks, and human history, all rolled into one stunning vista. It’s a reminder that even the things we see every day on our screens can have fascinating stories behind them.