This sedimentary rock has hardened over the years with sand shells, small pebbles, sand grains, and rocks of various sizes. Compared to our 4.5 billion year old Earth, these sand shells might as well be brand new, when in reality they could be up to 1,000 years old. If the sandstone were to be replaced by calcite this would completely change the rock subclass, then it would be chemical and organic limestone. Variation in sandstone is due to different deposition rates and changes in sediment movement patterns (McKnight, p. 384). These tightly packed stones and shells will be weathered by wind and waves over time and could eventually be reduced to a rock the size of your hand. The image above shows an extrusive volcanic igneous rock known as andesite. They were imported here to Laguna Beach to help minimize erosion (Merton Hill, p. 10-11). Extrusive igneous rocks form on the Earth's surface due to the rapid cooling of lava or mixing with different materials such as ash or cinders from an eruption. There are two different types of extrusive igneous rocks; Plutonic and Volcanic. Andesite is known to be gray in color and made up of very coarse grained textures, making it much more difficult to break down than sedimentary rocks. Unlike loose gravel and other sediments, igneous rocks are known to be able to slow seismic waves from earthquakes, causing less damage to surface structures. The picture above shows the big difference there can be in animals, on the right is Emerita Analoga (sand crab), and on the left is Zalophus Californianus (California sea lion). The sand crab is an invertebrate while the seal is a vertebrate and a mammal. Invertebrates make up 90% of all... middle of paper ... and violet wavelengths are the shortest, and violet is the least visible to the human eye. These wavelengths are scattered throughout the day and caused by a redirection of the direction of light waves due to gas molecules present in the atmosphere (McKnight, p. 84). When the sun sets towards the end of the day, few blue wavelengths remain and we see orange and red which are dominant and the longest wavelengths of light visible to the human eye . At the bottom of the photo (closest to the setting sun), red and orange are the dominant colors visible with blue and almost purple at times. If our eyes couldn't see orange and red, our sunsets would be dark blue or black. Works Cited Hess, D., McKnight, TL and Tasa, D. (2011). McKnight's Physical Geography (custom edition for California State University, Northridge; 2nd California ed.). New York: learning solutions.