Pumice is so light it can float on water! Photo via Flickr.
Did you know that there is a floating ‘island’ of rock in the south pacific ocean? The world is full of awesome rocks and here are some amazing rock facts.
I was astounded when I came across the fact that the New Zealand navy found a pumice ‘island’ or raft floating in the ocean. That got me wondering what other cool rock facts there are. I did some research and now want to share some of the amazing and interesting facts that I found about rocks throughout the world and the Rocky Mountains.
10 Cool Rock Facts
Most fossils are discovered in sedimentary rocks, especially in rocks that were once underwater.
The lightest rock is pumice, so light that it can float on water. Here is a cool video that shows a huge amount of pumice floating on a lake in Chile shortly after a volcanic eruption. Similar events have happened in the Pacific Ocean, creating floating ‘islands’ of pumice.
A beautiful geode. Photo via Flickr.
Geodes are dull balls of igneous or sedimentary rocks on the outside, but beautiful crystals on the inside. The coolest part of geodes is that you can go geode hunting near you! The hard part is guessing which rocks contain amazing crystals and which don’t. Do some research and you can find good areas to go geode hunting. We’ve done some geode hunting with our kids and had moderate success. Unfortunately, most of the rocks we found weren’t geodes, but we did fine some very cool ones that we still have.
Rocks have helped scientists figure out how old the Earth is. Researchers used some of the oldest rocks on the Earth along with meteorites to guess how old the Earth is. They estimate the Earth is about 4.54 billion years old! That is 4,540,000,000 years old.
A rock is a naturally occurring solid that is made up of one or more minerals. Read more about minerals here. If you look closely at a rock you can see that it’s made up of lots of tiny pieces. You can use these tips here to help you figure out what kind of the three main types of rock it may be.
Shale is the most abundant sedimentary rock in the world. In fact, it makes up about 70 percent of all sedimentary rock in the Earth’s crust. Of the three main kinds of rocks (igneous, sedimentary, and metamorphic), sedimentary is the most common and makes up the majority of rocks exposed on the Earth’s surface. Read about the rock cycle here.
Corona Arch in sandstone in Southern Utah. Photo courtesy of Karen Danenhauer.
Sandstone is the second most abundant sedimentary rock. It is easily weathered and eroded by wind and water to create amazing rock formations such as arches and slot canyons.
Giant’s Causeway. Photo courtesy of Giuseppe Milo.
Some special rocks form when magma cools in certain ways that create weird polygonal shapes. The shapes can be straight or bent. One great example of how these rocks formed naturally is Giant’s Causeway.
Rocks are just about the most solid substance on Earth, but they are changing all of the time, even mountains grow taller or shorter all the time. These changes are just on such a slow pace that it’s hard for us to notice. For example, the Himalayas are growing by about 2.4 inches every year and the Appalachian Mountains in the US are very old and are slowly getting shorter due to erosion and weathering.
Rocks are solid and impossible to break with your hands. You can use a hammer or sledgehammer to break them apart though. Can you believe that water or plants can break a rock apart? Yes, water can break rocks apart by a freeze, thaw cycle. Water will seep into cracks in rock and sit there. Then overnight if the water freezes it expands (when water freezes it expands). This expanding action of water can break apart large rocks or boulders and over time the crack gets bigger and bigger. Plants can break rocks using their roots. The roots can sneak into cracks and slowly over time grow larger, causing the crack to get bigger.
root wedging…frost freeze cycle…