IE GSI Quaternary Sediments 50k Ireland (ROI) ITM Download

In terms of time scale in geology, Quaternary is the present-day time and it began 2.6 million years ago. A lot of this time period relates to the Ice Age. Quaternary sediments are the soft material that has been deposited during this time. In Ireland much of this is related to the movement of glaciers and ice sheets. The main types of sediments shown on the map are tills (boulder clays), gravels, sands and peat. Over most parts of Ireland, these sediments cover the bedrock (solid rock at or below the land surface). Geologists map and record information from the shallow sediments which can be seen at or near the surface. This information along with boreholes (a deep narrow round hole drilled in the ground), geophysical data (information on the physical properties of the Earth's surface and subsurface e.g. magnetics, gravity and electromagnetics) and geochemical data (chemical properties) is used to create the map. Areas are drawn on a map to show where sediments are found. We collect new data to update our map and use data made available from other sources. This map is to the scale 1:50,000 (1cm on the map relates to a distance of 500m). It is a vector dataset. Vector data portray the world using points, lines, and polygons (areas). The sediments data is shown as polygons. Each polygon holds information on the sediment type, sediment code and its unique identifier.从地质时间尺度来看，第四纪（Quaternary）是当前的地质时代，其起始时间为260万年前。该地质时期的绝大多数时段与冰期相关联。第四纪沉积物是该时期沉积形成的松软物质。在爱尔兰境内，此类沉积物多与冰川及冰盖的运动相关。该地图展示的主要沉积物类型包括冰碛物（tills，即漂砾黏土）、砾石、砂及泥炭。爱尔兰绝大多数区域的基岩（bedrock，即地表或地表以下的硬质岩石）均被此类沉积物覆盖。地质学家会对地表或近地表处出露的浅部沉积物开展地质填图与信息记录工作。此类信息与钻孔（boreholes，即地面钻凿的深窄圆孔）数据、地球物理数据（涵盖地球地表及地下的物理性质相关信息，例如磁法、重力与电磁法数据）以及地球化学数据（化学性质相关数据）一同被用于绘制该地图。地图上绘制的多边形区域用于标识沉积物的赋存位置。本团队会采集新数据以更新该地图，同时也会使用其他渠道公开的相关数据。该地图的比例尺为1:50000（即地图上1厘米对应实地距离500米）。本数据集为矢量数据集（vector dataset）。矢量数据通过点、线与多边形（即区域）来刻画地理空间。沉积物数据以多边形图层形式展示，每个多边形均包含沉积物类型、沉积物编码及唯一标识符等信息。