Geography Summaries: Rising Sea Levels and Coastal Landscapes PDF

GEOGRAPHY SUMMARIES PARAGRAPHS 2 AND 3 Paragraph 2: Rising sea levels Warming climate and rising seas The Holocene began around 12,000 years ago. The climate warmed up quickly. Land ice melted and sea levels rose because of this. The North Sea filled up with water, causing a smaller and smaller c...

GEOGRAPHY SUMMARIES PARAGRAPHS 2 AND 3 Paragraph 2: Rising sea levels Warming climate and rising seas The Holocene began around 12,000 years ago. The climate warmed up quickly. Land ice melted and sea levels rose because of this. The North Sea filled up with water, causing a smaller and smaller coastline. A period which is marked with an increase of sea influence is called a marine transgression. Melting ice wasn’t the only reason for rising sea levels: Subsidence also contributed. The weight of land ice had pushed the Earth’s crust downwards in Scandinavia. While the ice melted, the crust began to rise slowly. This is a process that is still continuing today. It works a bit like seesaw: Scandinavia went up, and the ground in northern Netherlands went down. Together, subsidence and melted ice caused a sea level rise in the Holocene. This happened quickly first, then slowed down after. Rising sea levels also led to wetter conditions in the Netherlands (think about more floods, rainfall, etc.) The water table (A limit of groundwater) rose till it reached the surface, creating a marshy environment where the remains of a dead plants didn’t decompose fully yet (We call this peat) The actual term for this is basal peat and it’s the first layer of peat that was created in the lowest parts of the Netherlands in the Holocene. Coastal mudflats Sea levels continued to rise but luckily muss less quickly than before. Low sand masses that we know as beach ridges formed parallel to the coast. Tops of these ridges emerged from the water, which allowed wind to blow the dry sand into dunes. These dunes are old dunes and we can still find these today. Let’s talk about the tide, which is the daily rise and fall of sea levels. Now something about inlets, which are gaps between the beach ridges. The current was quite strong and fast, causing only the largest, heaviest particles to sink to the bottom. Finer particles from clay were deposited further away. The deposits of sand and clay that had formed in mudflats behind dunes are called old marine clay. Think about it as old slay that was from the sea which are in mudflats behind dunes. Peat bogs Now we’re going to talk a bit more about peat and peat bogs. As mentioned earlier, peat is a marshy environment where the dead plants haven’t decomposed fully yet, and this is called basal peat. Let’s start. From 3850 BC onwards, the sea level rise slowed even more. Now, in the west of the Netherlands, new rows of beach ridges started to form. In the mudflats behind the dunes behind the dunes, the influence of salt sea water started to lessen. Because of this, the allowance of water plants started to grow. Areas that used to be open with water quickly turned into ‘’forests’’ with plants. When these plants died however, they didn’t decompose fully but instead formed a layer of peat. Over time, plant growth and peat development caused open water to become land. This process is called land formation. The thick layer of peat that developed in this period is known as Holland Peat. Peat doesn’t just form in the areas where sea levels are rising. It could also be formed in wetlands where rainwater cant sink due to a sort of layer where water can’t pass through. The water remains on the surface, which creates perfect conditions to grow water plants. Peat-forming wetlands like these that are fed with only water are called bogs. Wetlands that are fed with groundwater are called fens. Later deposits The loose peat could be easily washed away during storms. As an result, the landscape had changed. It seemed like the sea had taken large “bites” out the coastline in the north and southwest of the country. As the sea rushed in the peat that remained got covered with a layer of sand and clay which we call young marine clay. Young dunes also got formed, by the freeing up of a lot of sand that the wind shaped into newly formed dunes. Paragraphs 3: Life along the coast Marine clay landscape Alright, on to the next part. The influence of the sea varied pretty much throughout the Holocene. First the sea expanded a lot inland (marine transgression) However, later the sea retreated and the coastline shifted outward again. (marine regression) allowing peatlands to expand. Unfortunately, in 800 AD, the sea became a bit aggressive again and boom! It flooded the coast in north and southwest of the Netherlands. As a result, young marine clay. The tides actually play a big part in this (the tide is the daily rise and fall of the sea). When there’s a high tide, the water is pretty still. This allows some fine particles of sediment to sink to the bottom. These particles of sediment that sink to the bottom are known as silt. Each time the tide comes in, it leaves a bit of silt, causing the ground level to rise. Over time, the area will transform above the water, making plants growing there. This is known as salt marsh. Terps are artificial mounds made of earth and waste. The first terps were very small, but as sea levels rose, they had to be built higher and higher. Now let’s talk about polders. Polders are formed by building a dike (sort of protection against sea) around a part of a salt marsh, which is also called a marine clay polder. Their fertile clay soils are now actually used for growing crops. They are also often divided into large plots of land that can be different shapes. It is a typical form of land division (dividing pieces of land). Farmers were allowed in some provinces to kind of claim a bit of land that got created. They did this by placings rows and kind of forming fences. This resulted in areas with calmer water, separating the clay and sand particles in the water and letting them sink to the bottom. This is also known as sedimentation. Peatlands Around 1000 AD, people began moving more to Dutch peatlands. They settled down by farms located along some central axis like a road. They would then dig a wide canal that is parallel to the original settlement. This method started the typical Dutch peat reclamation landscape, which consisted of peat polders divided into long and narrow strips. First, farmers used the drained peatlands to grow crops, however, removing the water caused loose peat soil to become some sort of compacted, which became a problem known as peat collapse. The plant matter that had once been under water, was now exposed to the air so it began to decompose. The soil became too wet for farmers which meant they had to start livestock farming. Drainage polders In the 16th century, people started creating new land called drainage polders, by draining lakes, ponds, and parts of the sea. Drainage polders are located in former peatlands where all the peat has been washed away or dug up, finding an underlayer of old marine clay. As a result of this drainage polders are known as a marine clay landscape.