Lab 8 COMPLETED

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Apr 3, 2024

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Name:dej Date 02/25/2024 Class Day/Time 12:52 pm Lab 8: A Tale of Two Beach Faces – Florida Beach Sediment Comparison Lab As a student living in the state of Florida, you have likely experienced a sandy beach before. However, you may not have recognized that there are some significant differences between the beaches of the west coast, along the Gulf of Mexico and the East Coast, facing the Atlantic Ocean. The sands of each of the beaches have different grain sizes, textures, and colors – why? The laboratory exercise objective today is to recognize the major differences between provided lab samples of sand from the west coast and east coast of Florida. Through this, you will also relate these differences to wave action and the angle of the beach face at each of the respective locations. Beach Sand and the Wentworth Scale Sand is a reference to a specific size of sediment, ranging between 1/16 and 2 millimeters in diameter. Most beach sand, as much as 90%, is derived from sediment-carrying rivers that deposit materials near the coast. As the heavier materials, such as gravel, are usually deposited upstream, much of the smaller materials are prevalent closer to the coast. The finest material, such as silt or clay, is usually suspended in the water and carried out to the open ocean. Once deposited, sand on beaches are distribu ted by wave action and a process called “longshore drift,” where sand is carried up shorelines since waves refract when approaching the shallow depths adjacent to shorelines. Quartz makes up a vast majority of beach surfaces, especially along the west coast of Florida as it is a widely abundant material that is fairly resistant to weathering. Along the east coast, however, the beaches contain a significant amount of carbonate materials, causing the sand to look tanner in color, than the white sand of the west. Carbonates along the east coast are mostly made up of broken pieces of shells that have been continuously broken down and rounded off by waves. To adequately measure grain size, a scale is used called the Wentworth Scale of Grain Size. Familiarize yourself with this scale below: Sieving In order to measure the distribution of grain sizes from a beach sample, we will undergo a process called, “sieving” (s -iv-ing). A sieve (siv) is a container with a mesh base that has specific sized openings. Sieves are stacked on top of one another, with the largest opening mesh sieve stacked at the top and the smallest at the bottom. Sediment is poured into the top of the stack and shaken, to allow for the sediment to settle and be sorted by grain size. Once complete, the sieve set is separated, and each pan is compared to the total sample size to determine the percentage of sediment across each size in the scale.

Data Display A histogram is created to graph the frequency distribution of the sediment sample. In this lab, you will create histograms to represent each of the sample – west coast and east coast. The Beach Face – Angles The slope of the beach, which is related to wave action, is referred to as the beach face. This angle, which is measured from the horizontal, gives us clues about the sediment grain size and the amount of wave action that occurs in the area. Beaches with a very shallow slope, typically contains much finer sediment. This is because a lack of intense wave action means that the finer sediment has not been carried away from the beach. Conversely, where beaches have courser sediment, much of the finer materials have already been eroded away due to a significant amount of wave action in the area. Laboratory Procedures 1. Record the sample name (west coast or east coast). Measure out exactly 100g of your sample using the laboratory balance. 2. Examine your sieve set - make sure they are free from loose sediment and that they are stacked in order from largest opening size to smallest. 3. Pour the sediment sample into the top of the set and shake it (back and forth, not up and down) to allow the sediment to be properly sorted for approximately 15 minutes. 4. Carefully separate your sieve set and measure the mass of each of the sieves separately. Record your measurements in the table. 5. Follow steps 1-4 for the other sample. Lab Part 1: West Coast Sample Starting Sample Mass (g): _ (g): 100g A B C D Sediment Sample Grain Size Mass (grams) Mass (g) / Total Sample Mass (g) Column C x 100 (Percent of Total) Gravel >2mm 0g 0g 0% Very Coarse Sand 1-2mm 0g 0g 0% Coarse Sand 500 μm – 1mm 1g 0.01g 1% Medium Sand 250 μm – 500 μm 40g 0.4g 40% Fine Sand 125 μm – 250 μm 53g 0.53g 53% Very Fine Sand <125 μm 2g 0.02g 2% Note: 1 millimeter = 1000 micrometers

Calculate the sum of the masses in Column B: 0.96 Calculate your percent error (100g (Original Mass) - Sum of Masses in Column B / 100g (Starting Sample Mass) x 100 = 4%. What could account for the change in mass (the percent error calculated) in the steps of the laboratory exercise? The sand grains could account for the mass. Lab Part 2: East Coast Sample Total Sample Mass (g): _____100 g____________ A B C D Sediment Sample Grain Size Mass (g) Mass (g) / Total Sample Mass (g) Column C x 100 (Percent of Total) Gravel >2mm 0g 0g 0% Very Coarse Sand 1-2mm 1g 0.01g 1% Coarse Sand 500 μm – 1mm 59g 0.59g 59% Medium Sand 250 μm – 500 μm 39g 0.39g 39% Fine Sand 125 μm – 250 μm 2g 0.02g 2% Very Fine Sand <125 μm 0g 0g 0% Note: 1 millimeter = 1000 micrometers Calculate the sum of the masses in Column B: 101g (100g (Original Mass) - Sum of Mass Column B / 100g (Starting Sample Mass) x 100 = -1 Data Analysis Generate histograms for each of the two samples. Each row in the histogram represents 5% of the total sample. Histogram – West Coast Sample Grain Distribution A B Sedimen t simple size grain Mass Grams

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0g Gravel> 2mm 0g 0g Very coarse sand1- 2mm 0g 1g Coarse Sand 500 μm – 1mm 1g 40g Medium Sand 250 μm – 500 μm 40g 53g Fine Sand 125 μm – 250 μm 53 g Very Fine Sand <125 μm 2g Total=96 g

clay and silt very fine sand fine sand medium sand coarse sand very coarse sand gravel Histogram – East Coast Sample Grain Distribution A B Sedimen t simple size grain 0g 2g 39g 59g 1g 0g Gravel> 2mm 0g Very coarse sand1- 2mm 1g Coarse Sand 500 μm – 1mm 59g Medium 39g

Sand 250 μm – 500 μm Fine Sand 125 μm – 250 μm 2g Very Fine Sand <125 μm 0g clay and silt very fine sand fine sand medium sand coarse sand very coarse sand gravel Analysis Questions Compare and contrast the grain size distributions presented in your histograms for the two beach samples. When it comes down to the west coast grain size distribution the histogram demonstrates that a large amount of fine sand and medium sand are found on beaches.

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Based on grain size distribution and the pre-reading, describe the expected differences in wave energy of both beaches. The differences in wave energy between the beaches on the east and west coasts should be the west coast beach handless wave energy since theirs is a lot of fine sand left over. But the east coast however, would experience high energy erosion since there is less sand there. The presence and sorts of sediment’s are determined by the energy that strikes a beach.

Lab 8 COMPLETED

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