1 00:00:00,180 --> 00:00:14,820 This is Earth, home to seven billion plus people, seven continents, and all kinds of 2 00:00:14,820 --> 00:00:16,739 amazing plants and animals. 3 00:00:16,739 --> 00:00:20,420 This is what Earth has looked like for a long time, and will probably continue to look like 4 00:00:20,420 --> 00:00:21,620 for a long time. 5 00:00:21,620 --> 00:00:22,620 Right? 6 00:00:22,620 --> 00:00:23,620 Yes. 7 00:00:23,620 --> 00:00:24,620 And no. 8 00:00:24,620 --> 00:00:27,920 Sure, this is what Earth looks like from space, but even though it looks pretty much the same 9 00:00:27,920 --> 00:00:32,939 from whenever we view it from afar, once you zoom in on it, you can see it's always changing. 10 00:00:32,939 --> 00:00:36,899 On a small scale, things like moving water shape the Earth's landforms, the natural 11 00:00:36,899 --> 00:00:38,579 features of the Earth's surface. 12 00:00:38,579 --> 00:00:42,579 On a bigger scale, the gradual shifting of the Earth's crust is slowly moving even 13 00:00:42,579 --> 00:00:45,460 bigger things like the oceans and the continents. 14 00:00:45,460 --> 00:00:50,399 So one day, our planet will look different, maybe a lot different from how it looks now. 15 00:00:50,399 --> 00:00:53,640 So how exactly does water shape Earth's landforms? 16 00:00:53,640 --> 00:00:57,200 Or to bring it back to the spheres we've been talking about, how does the hydrosphere 17 00:00:57,200 --> 00:01:02,750 affect the geosphere? 18 00:01:02,750 --> 00:01:05,090 To understand that, we need to discuss weathering. 19 00:01:05,090 --> 00:01:09,090 I'm not talking about the weather, like if it happens to be sunny or cold or foggy 20 00:01:09,090 --> 00:01:10,530 outside your window right now. 21 00:01:10,530 --> 00:01:14,930 I'm talking about weathering, the process that takes place as rocks and other parts 22 00:01:14,930 --> 00:01:17,989 of the geosphere are broken down into smaller pieces. 23 00:01:17,989 --> 00:01:22,769 Weathering can be caused by water, air, chemicals, plants, or even animals, including us. 24 00:01:22,769 --> 00:01:26,189 And there are two types of weathering you need to know about, mechanical weathering 25 00:01:26,189 --> 00:01:27,709 and chemical weathering. 26 00:01:27,709 --> 00:01:31,250 Mechanical weathering is the process of breaking big rocks into little ones. 27 00:01:31,250 --> 00:01:36,909 Frost, ice, the roots of plants, running water, or heat from the sun can all cause mechanical weathering. 28 00:01:36,909 --> 00:01:41,430 Chemical weathering involves the changes that some substances can cause in the surface of the rock 29 00:01:41,430 --> 00:01:43,349 that make it change shape or color. 30 00:01:43,349 --> 00:01:47,769 Things like carbon dioxide, oxygen, and acids can all cause chemical weathering. 31 00:01:47,769 --> 00:01:54,290 And when rocks have been weathered and all broken down and are later moved by natural forces like wind, water, or ice, 32 00:01:54,290 --> 00:01:55,590 that's called erosion. 33 00:01:55,590 --> 00:01:58,290 Weathering and erosion sound pretty similar, right? 34 00:01:58,290 --> 00:02:00,670 Well, yeah, but not exactly. 35 00:02:00,670 --> 00:02:03,370 Think of weathering as the hammer that breaks down the rocks. 36 00:02:03,709 --> 00:02:06,629 Erosion is the process that carries those rock fragments away, 37 00:02:06,969 --> 00:02:08,590 or put in a way we're all familiar with. 38 00:02:08,889 --> 00:02:11,969 Weathering helps make a mess, and erosion helps clean it up. 39 00:02:12,050 --> 00:02:16,310 Let's take a trip to the beach to see what part the hydrosphere plays in weathering and erosion. 40 00:02:20,479 --> 00:02:25,360 This is a picture taken from space of the coastline of Massachusetts in the northeastern United States. 41 00:02:25,539 --> 00:02:27,400 It's part of a landform called Cape Cod, 42 00:02:27,560 --> 00:02:31,120 and the picture shows what the beaches and islands around it looked like in 1984. 43 00:02:31,400 --> 00:02:33,400 Now look at this photo from 2014. 44 00:02:33,960 --> 00:02:34,960 What's different? 45 00:02:34,960 --> 00:02:38,919 There are actually more islands in 2014 than there were before. 46 00:02:38,919 --> 00:02:42,719 Back in 1984, that long strip of land was North Beach. 47 00:02:42,719 --> 00:02:46,159 Now, that strip of land has been chopped up into separate islands. 48 00:02:46,159 --> 00:02:50,479 The top part is North Beach, the middle area broke off into North Beach Island, and the 49 00:02:50,479 --> 00:02:52,639 bottom part is now called South Beach. 50 00:02:52,639 --> 00:02:54,560 So, how did that happen? 51 00:02:54,560 --> 00:02:59,139 Well, moving water is a major cause of erosion, and there's a lot of moving water in the 52 00:02:59,139 --> 00:03:00,360 Atlantic Ocean. 53 00:03:00,360 --> 00:03:05,259 The intense energy of ocean waves crashing on shore causes pieces of the rocky, sandy 54 00:03:05,259 --> 00:03:09,180 coastline to break into smaller pieces, or to weather over time. 55 00:03:09,180 --> 00:03:14,319 Then, natural forces like major storms and rising sea levels then move or erode these 56 00:03:14,319 --> 00:03:15,740 smaller pieces. 57 00:03:15,740 --> 00:03:20,280 Day to day, you might not notice any dramatic changes, but over the course of 30 years? 58 00:03:20,280 --> 00:03:24,199 Well, as these pictures show, coastlines can change a lot. 59 00:03:24,199 --> 00:03:26,860 So what can we take away from this? 60 00:03:30,379 --> 00:03:32,340 Well, we saw that water can weather 61 00:03:32,340 --> 00:03:35,860 and erode Earth's landforms, and that's just one example. 62 00:03:35,860 --> 00:03:38,919 There are so many others, like floods weathering valleys 63 00:03:38,919 --> 00:03:41,020 or glaciers eroding mountains. 64 00:03:41,020 --> 00:03:43,300 Let me break it down for you this way. 65 00:03:43,300 --> 00:03:44,419 See what I did there? 66 00:03:44,419 --> 00:03:48,000 The hydrosphere shapes and sometimes moves the geosphere. 67 00:03:48,000 --> 00:03:50,219 One last joke before I sign off. 68 00:03:50,219 --> 00:03:52,840 What did the geosphere say to the hydrosphere? 69 00:03:52,840 --> 00:03:54,699 You crack me up.