Physiographic Units Level 1 1:250,000 Ireland (ROI) ITM

The term Physiography can be described as a blending of “physical" and "geography". Physiographic Units show Ireland’s physical landscape divided into categories such as ‘Bedrock plain’ and ‘Flat to undulating sediments’. Areas are grouped based on bedrock geology (solid rock at or below the land surface), Quaternary (largely Ice Age) sediments and geomorphology (landforms). Digital Elevation Models (DEMs) and Aerial photography are also used. Three maps were made, each giving a different level of detail. The Level 1 map has 7 categories. These show bedrock landscapes at different heights above sea level such as mountains (more than 300 m), hills (100 to 300 m) and plains (less than 100 m). Sediment (sand, gravel and soil) landscapes are grouped by slopes, such as rolling (gentle hills), hummocky (small lumpy hills) and flat. The Level 2 map has 16 categories. These show bedrock landscapes with different texture (how rough or smooth it is) or rugosity (how wrinkly it is), depending on the bedrock type (e.g. granite bedrock evolves into rounded mountains or hills). Sediment (sand, gravel and soil) landscapes are grouped by the type of geological process shaping them eg (Drumlin and ribbed moraine topography). The Level 3 map has 29 categories. This is the most complex and further categorises in a similar way to level 2. Areas were mapped at scales ranging from 1:30,000 to 1:100,000 (1cm on the map relates to 1km). The map is designed to be used at 1:250,000 scale (1cm on the map relates to 2.5km). It is a vector dataset. Vector data portray the world using points, lines, and polygons (areas). This data is shown as polygons. Each polygon has a unique identifier and its landscape category.地貌学（Physiography）一词可被诠释为“自然”与“地理学”的融合。地貌单元（Physiographic Units）呈现了爱尔兰的自然地貌分区，涵盖“基岩平原”“平缓起伏沉积物区”等类别。区域的划分依据包括基岩地质（地表或地表以下的固态岩石）、第四纪（以冰期沉积为主）沉积物以及地貌学（地表形态），同时还采用了数字高程模型（Digital Elevation Models, DEMs）与航空摄影数据。 本次研究共制作了三张地图，每张地图的地貌细节精细程度各有不同： 一级地图共包含7个分类，其基于海拔高度对基岩地貌进行划分，涵盖山地（海拔高于300米）、丘陵（海拔100至300米）和平原（海拔低于100米）等类型；沉积物（砂、砾石与土壤）地貌则按坡度特征分组，包括缓坡丘陵、圆丘状（小型凹凸丘陵）和平坦地貌等类别。 二级地图共包含16个分类，其依据基岩类型，从纹理（表面粗糙或光滑程度）或粗糙度（表面褶皱程度）两个维度对基岩地貌进行呈现，例如花岗岩基岩会演化形成圆润的山地或丘陵；沉积物（砂、砾石与土壤）地貌则按塑造其形态的地质作用类型进行分组，例如鼓丘与脊状冰碛地貌。 三级地图共包含29个分类，是本次数据集最为复杂的版本，其延续二级地图的分类逻辑进行进一步细分。 本次制图的比例尺覆盖1:30000至1:100000（即地图上1厘米对应实地1公里），该地图推荐使用1:250000的比例尺进行使用（地图上1厘米对应实地2.5公里）。 本数据集为矢量数据集，矢量数据通过点、线与多边形（区域）来表征地理空间。本次数据以多边形形式呈现，每个多边形均配有唯一标识符及其所属的地貌类别。