Graphic with dinosaur footprints and a magnifying glass. Text reads" Geo Q&A: Where are the dinosaurs?" There is a missing poster with a dinosaur on it beside the text.

Where are the dinosaurs?

Dinosaurs were some of the biggest animals to ever roam our planet. This massively large group of reptiles were around from the late Triassic Period (approximately 230 million years ago) until they went extinct at the end of the Cretaceous Period, approximately 65.5 million years ago (not including their flying descendants, which evolved into today’s birds!). For a remarkable 165 million years, they were seemingly ubiquitous; dinosaur fossils have been found on every continent! When dinosaurs first evolved, Earth’s plates were arranged into one large continent called Pangea. This single-continent arrangement no doubt facilitated their migration to all corners of the globe. It should stand to reason therefore that if I start digging in my backyard here in London, Ontario, I should eventually find some kind of dinosaur fossil, should it not? Turns out, the answer is a disappointing no. Only disappointing, though, if dinos are your only area of interest. Don’t get me wrong, I love dinosaurs (although I would not want to meet one in a back alley. Or even a front alley); however, there is still a treasure trove of fossils just waiting to be uncovered here in Ontario. The fossils here are just much, much older than any dinosaur, because the time they lived in and thus the rocks that their remains eventually became fossilized within are much older. The rocks in southwestern Ontario range in age from the late Ordovician Period (about 455 million years) to the Late Devonian Period (about 360 million years). That is roughly 205-130 million years before the first dinosaur strutted on the scene! If there are no dinosaur fossils to be found in southwestern Ontario, does this mean that dinosaurs never lived here at all? Fear not. Ask any paleontologist, and they will all agree that dinosaurs almost certainly did live in what is now Ontario, Canada. The Mesozoic Era, sometimes colloquially called the Age of the Dinosaurs, lasted approximately 165 million years. During such a long geological time span, there were no doubt times of deposition that added to the rock record. Given that there would have been many billions of individual dinosaurs during that time, the remains of many little and big critters would have absolutely been buried in the sediments and later undergone fossilization across Ontario. So, the big question remains: where are the dinosaurs? Up until about 2.5 million years ago, these fossilized dinosaur bones were likely still in the rocks in southern Ontario, just waiting to be discovered by future paleontologists. But then something big happened. Something really big. Things started to get very cold. Global temperatures began to drop significantly, and ice sheets started to grow on the continents. The cause of this change to colder conditions isn’t as clear as you’d think for something that occurred relatively recently (at least in geological terms that is). If you ask three different respected geologists why, you might get three slightly different respectable answers. That doesn’t mean that two of them are wrong, it just means that the cause is likely a result of an interplay of different factors that all contributed to lower global temperatures. The position of Earth’s continental plates no doubt played a big factor in the overall cooling of the planet, as their arrangement greatly affects oceanic and atmospheric circulation patterns. Other variables such as atmospheric CO2 levels and even predictable changes to Earth’s orbit could have facilitated the cooling process.   In North America, the Laurentide ice sheet covered most of Canada and some parts of the United States a number of times, as it advanced and retreated repeatedly in cycles of growth and shrinkage in response to climatic conditions. You can imagine the havoc that a sheet of ice reaching a few kilometres in thickness would have on the ground as it makes its way forward and backward! The ice sheet literally scraped many layers of rock away, turning whatever got in its way into a fine powder called “rock flour”.  All those poor dinosaur fossils that waited so patiently to get their place of honour in a paleontology museum were instead ground up into dust. Far be it from the scientific community to see this as a bad thing. Although glacial activity removed the fascinating rocks layers of the dinosaur-saturated Mesozoic Era here in Ontario, it ended up exposing the just-as-fascinating rock layers of the even older Paleozoic Era! The rocks that lie at or near the surface in southwestern Ontario range in age from the Upper (or late) Ordovician Period (about 455 million years old) around the Belleville to Peterborough area and get progressively younger as you drive southwest towards the Arkona area, where they are late Devonian in age (about 360 million years old). Although the fossils found in these rocks differ among species, there are many common types of fossils found in many of the limestone, dolostone, and shale outcrops throughout southwestern Ontario, from Ordovician to Devonian rock units. Some of the most common types of fossils found in southwestern Ontario are corals. Although they look like plants, corals are actually marine animals that usually lived attached to the seafloor. The fossilized corals here in southwestern Ontario are either tabulate (colonial-type) or rugose (solitary and colonial type) corals, and if you find them, it can tell you quite a bit about what the environment was like when they were alive. Since they thrive in relatively shallow, warm, marine seas, we can reconstruct their living conditions and make some accurate conclusions about the environment when these rock units were deposited. There are also many other fossils to be found in these rocks, such as brachiopods, gastropods, bivalves, crinoid parts, trilobites, bryozoans, and much more. The animation here shows what life could have looked like in the shallow, tropical seas of the Devonian Period, in southwestern Ontario. This is all fine and dandy, but the question still remains: where are the dinosaurs? To find them, you’ll need either a good-working car or a plane ticket; however, you

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Ice volcanoes on the shore of a frozen lake. Text on top reads: Geo Q&A What are ice volcanoes?

Geo Q&A: What are ice volcanoes?

If you’ve ever walked on the shoreline of one of the Great Lakes in the winter, you might have seen some inconspicuous mounds of ice on the water. These mounds, often forming in lines parallel to the shore, are known as ice volcanoes. Although they don’t spew fire like their rocky counterparts, if conditions are right, ice volcanoes can erupt icy cold water up to 10 metres high! They are typically conical in shape, like a stratovolcano, and have a hole going down the middle. What are the conditions for an ice volcano to form? Ice volcanoes can grow in a matter of hours—but only if the conditions are right. Usually, ice volcanoes only form on freshwater lakes because salt water has a lower freezing temperature. The lake must not be completely frozen, because they depend on wave action to form. It also must be cold enough outside for the spray from the waves to freeze into ice. If all these conditions are present, then there is the potential for an ice volcano to form. How do ice volcanoes form? Firstly, water freezes on the edge of the lake forming an ice shelf. The waves from the lake hit the ice shelf and go over and underneath it. When the water flows under the shelf, it sprays up through any cracks or holes in the ice. The spray from the water freezes on top of the shelf around any cracks or holes. If this process continues for long enough, the ice can grow into a mini volcano surrounding an existing hole! Where can I go to see them? If you want to see an ice volcano, be sure to keep a safe distance away and always stay on shore. The best place to see ice volcanoes is on the southern shores of Lake Erie and Lake Ontario. When the onshore wind is above 40km/hour and the temperature is below freezing, there are often rows of volcanoes by the shore. They can also form over sand bars or rocky reefs, although this is less common. This process is similar because the water is pushed upward under an ice shelf as it reaches shallower depths. From shore, you might even be able to locate a sand bar by the distinctive row of volcanoes on top of it. Why are ice volcanoes dangerous? Although icy cold spray from an erupting volcano may not be pleasant, the real danger from ice volcanoes is getting stuck inside one. If someone were to climb a volcano and fall inside the mouth, it would be extremely difficult for them to get out of the cold lake water surrounded by ice. Ice shelves are often unstable and cannot hold much weight. It is very important to never try to walk on an ice shelf or climb ice mounds.  Always view them safely from shore. Why are ice volcanoes important? Ice volcanoes are useful in helping protect shorelines from erosion caused by waves and storms. While this protection doesn’t last long because the life of an ice volcano is relatively short, their presence still contributes to reducing shore erosion. Geoscientists study how erosion impacts the stability of shorelines and slopes in order to protect infrastructure from damage. If you’re curious about how geoscientists research and protect oceans, lakes, rivers and groundwater, checkout this video from GeoscienceINFO.com: Can we see ice volcanoes in other places? The Great Lakes are an excellent location to see ice volcanoes, but that’s not the only place you’ll find these types of structures. Astronomers have seen similar formations on other planets and celestial bodies! Off Earth, these formations are called cryovolcanoes, literally meaning “cold volcano.” They don’t only spew water, they can also erupt other volatiles like methane and ammonia. How do cryovolcanoes form? Similar to ice volcanoes on Earth, the temperature must be cool enough to freeze volatiles like water, methane, and ammonia. This most often happens on planets on the outer edges of solar systems, like the dwarf planet Pluto, or on moons and asteroids. The essential elements of cryovolcanoes are the same as ice volcanoes on Earth: an icy cone with liquid erupting up from underneath. But the actual formation of cryovolcanoes can be quite different. It has been theorized that a process called tidal friction is responsible for the formation of some cryovolcanoes. Jupiter’s moon Europa is made up of a worldwide ocean of liquid water or slushy ice with an overlying icy crust. The liquid under the crust moves due to the gravitational pull of Jupiter, creating tides. The moving liquid puts pressure on the ice, making cracks and fissures. As the liquid sloshes through these cracks in the crust and freezes, cryovolcanoes grow around the cracks and holes. However, tidal friction isn’t the only possible explanation for the formation of cryovolcanoes. If the inside of a planet is hot enough, materials that are melted will rise to the surface and create cryovolcanoes, similar to how magma rises through the mantle on Earth. There are two potential sources of heat on these celestial bodies. The first is caused by the decay of radioactive elements creating radiogenic heat. The second is heat left over from the formation of the planet, called primordial heat. Why are cryovolcanoes important? Cryovolcanoes can tell us a lot about the makeup of celestial bodies. For example, the finding of a giant cryovolcano on Saturn’s moon Titan helped to explain a prexisting mystery of the moon. The atmosphere of Titan has a large amount of methane in it, but since methane breaks down in sunlight, there should be less methane in the atmosphere than there is. The presence of the cryovolcano suggests that the methane is replenished from the interior of the planet by eruptions from the cryovolcano. Cryovolcanoes can help scientists to understand the mechanisms that create formations on celestial bodies. The beauty of ice volcanoes If you want to see ice volcanoes in action, go to the shore of a Great Lake this winter.

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