Geological coastal map of Lower Saxony 1: 25 000 — Relief of the Holocene Base

Today’s coastal area with its landscape features, the islands, wadding and marshes, is geologically a very young structure that has only emerged in the last 8500 years under the influence of a sea level rise of about 25 m. The originally existing geest landscape, formed in the Ice Age, was flooded, partially redesigned and covered in varying thicknesses by holocene coastal deposits. These are mostly clay-sluffy, sometimes sandy cotton and brackish water sediments, which are loaded into the coastal area by the sea and rivers, or peat which have been accumulated in coastal bogs. In the area of the islands, this up to 35 m thick sediment body is superimposed by dunes that reach up to 25 m in height. The Geological Coast Map of Lower Saxony 1: 25 000 presents the holocene landscapes and coastal deposits in two maps covering the following topics: — Relief of the Holocene Base — Profile types of the coastal holocene. The relief of the Holocene base is depicted in the form of a NN-related depth line plan, where the individual isolines mark depth levels of 1 m, while area colors summarise depth ranges of 2 m each. Map sections for which no statements can be made regarding the relief of the holocene base are characterised by light blue surface color. If a map sheet includes geest areas, these are displayed without surface color. In much of the coastal area, the Holocene base area corresponds to the former land surface formed in the Ice Age. In some places, however, this original relief was overstated by the holocene sea flooding and the associated erosion processes. Exposed parts of the original geest landscape were extensively removed under the influence of sea passage and surf, former valley systems were expanded by tidal currents, deepened and partly transformed into inland erosion channels. As sea level rise progressed, the original landscape forms and the areas redesigned in the Holocene were equally covered by young coastal deposits. Due to these conditions, the holocene base surface forms a geotechnically important interface between viable glacial moraine, meltwater and river deposits in the lying and repositionable holocene soft or loose deposits in the slope end.如今的滨海区域及其地貌特征——岛屿、潮滩与沼泽——从地质维度而言属于极为年轻的地质构造，仅在过去8500年间，受约25米海平面上升的影响方才形成。原本存在的、形成于冰河时期（Ice Age）的冰碛台地（geest）景观被海水淹没，经部分改造后，被全新世（Holocene）滨海沉积物以不同厚度覆盖。这些沉积物多为黏土质粉砂，间或为砂质粉砂与咸淡水混合沉积，由海洋与河流搬运至滨海区域；或是在滨海沼泽中堆积形成的泥炭。在岛屿区域，这套厚度可达35米的沉积体之上，叠加了高度最高达25米的沙丘。下萨克森州1:25000地质海岸图（Geological Coast Map of Lower Saxony）以两幅专题地图展示了全新世地貌与滨海沉积物，涵盖以下主题：— 全新世基底地貌— 滨海全新世剖面类型。全新世基底地貌以关联德国标准海平面（Normalnull, NN）的深度等值线图形式呈现，其中单条等值线代表1米的深度层级，而面状色彩则将深度范围按每2米为一档进行归纳。未明确全新世基底地貌的图幅区域以浅蓝底色标注。若某幅地图包含冰碛台地区域，则该区域不填充底色。在多数滨海区域，全新世基底对应冰河时期形成的古地表。但在部分区域，该原始地貌因全新世海侵及伴随的侵蚀作用发生改变。原本裸露的冰碛台地景观区域在海浪与潮汐的作用下被大规模移除，原河谷系统经潮流作用拓宽、加深，部分被改造为内陆侵蚀水道。随着海平面上升持续推进，原始地貌形态与全新世改造过的区域均被年轻的滨海沉积物覆盖。受上述地质过程影响，全新世基底表面构成了工程地质上的重要界面：其下为可开发利用的冰碛物、融水沉积物与河流沉积物，其上则为坡脚处易变形的全新世软质或松散沉积层。