Block Diagrams
A Block Diagram shows the topography of a block of land. It provides a 3-D picture of heights in 2-D form. It is often accompanied by cross and long sectional information. Geological block diagrams may also show sub-surface juxtaposition of strata at different depths.
Location Maps
Locating a site is often the simplest role played by a map.
The Dark Peak fieldwork list page includes many simple locator maps to accompany more complex sources of spatial information.
In newspapers this locating function is often used by editors to place a story and the tiny locator map is the most common map found in broadsheet newspapers served on the web or available in hard copy.
Field surveys
Field data comprise information collected with a specific end in mind and are a primary source, rather than a secondary source of information.
Manually collected spatial data may be collected by manual field surveying using plane tables, levels & theodolites, with results plotted on paper.
More recent digital methods include Electronic Distance Metering (EDM) and data logging, sometimes with hand held laser range finders. Satellite-based navigation systems allow a very cost effective acquisition of field data. Global Positioning Systems (GPS) receivers may be linked to data loggers to record position and routes automatically in a digital form. Grid references can then be stored in one field in a database and linked to other descriptive data about the same record.
Illustrations
Illustrations include all other illustrative materials on the Dark Peak web site that have no implicit spatial aspect. These mostly comprise line drawings.
Profiles
A profile is a section in two dimensions, usually showing elevation. They may be drawn using data from field surveying, a digital elevation model or a topographic map.
Good examples are associated with geological maps, for instance, showing how strata are related to one another below the surface. Other examples on this web site show the long profiles of landslides or the cross profiles of valleys, annotated to show vegetation associations with altitude.
Thematic Maps
A thematic map shows the spatial distribution of data associated with a specific subject, such as geology, soils, terrain, crime incidence, population density or voting behaviour.
The map may be qualitative in nature (e.g., predominant vegetation type, rock type; etc) or quantitative (e.g., percentage population change).
Thematic maps are usually generated for a particular purpose and can be generated as the result of analyses of other datasets which then allows for a focused use. These analyses are often carried out within a Geographical Information System. Amongst the specialist themes that are often mapped are:
- earth science themes of many kinds e.g. solid and drift geology;
- soils;
- land cover;
- land use and landscape;
- hydrology;
- flood risk;
- pollution sources;
- socio-economic characteristics;
- weather and climate;
- transport;
- administrative units;
- navigation;
- recreation; and
- education measures.
Thematic datasets are increasingly served over the web and may be mapped and explored by the user. For example interactive mapping sites include the Environment Agency Maps and the Emissions maps from the National Atmospheric Emissions Inventory. Thematic maps are often produced by governmental and non-governmental agencies in support of their day-to-day activities.
Neighbourhood socio-economic mapping of the UK may also be accessed over the web from Neighbourhood Statistics site.
Topographic Maps
Topographic maps and data depict general characteristics of physical and cultural detail. They usually include information about relief, land cover, hydrological features, lines of communication, boundaries, settlements and place names, along with geodetic information such as the National Grid. Although a number of map producers provide topographic maps, the most well known and heavily used are those produced by the Ordnance Survey (OS), Great Britain's national mapping agency. Specifications of topographic mapping continue to vary from country to country: different surveys produce varying scales, content, designs and coverages, see for example the USGS maps on the USA’s topozone.com site.
In Great Britain, printed topographic maps continue to be available in hard copy and aimed at leisure markets, such as the 1:50 000 scale Landranger, or the 1:25 000 scale Explorer series in Great Britain.
A scale of 1:10 000 means that 1mm on the map will be equivalent to 10 000mm (10m) on the ground. Large scale maps are where objects are shown to be relatively large (and usually more detailed). These tend to be 1:10 000 and less. Small scale maps fit large areas on to one map as each object is shown to be relatively small. So, 1:50 000 maps which show whole areas of cities in one go would be considered small scale compared to a 1:10 000 map.
Raster scanned versions of these general purpose maps may also be served from a number of sites on the World Wide Web, including Multimap. These datasets are also freely available to University students through the EDINA service so that OS data can be used with Geographical Information Systems for coursework and for dissertations.
Topographic data themselves may be served as a backdrop to other thematic data. Some of the older functions offered by topographic mapping such as car navigation are increasingly served by route-planning software e.g. from the AA.
Census Data
Census data are collected for predefined geographical units.
There are many different geographies that these data may be mapped against. Many are arbitrary political or social units such as:
- Administrative.
- Electoral.
- Postal.
Others may be mathematically derived blocks such as points or areas derived from for example the National Grid. For further information about these boundaries see the National Statistics. Census data can be obtained through the National Statistics site or through the Casweb service and provides information about demographics. Boundary data to support coursework and dissertation research is freely available through the Edina UKBORDERS service. Each of these geographies may have different scales.
For example in census geography these may be at increasing levels of detail:
- Country.
- County.
- District.
- Ward.
- Enumeration District.
To understand these boundaries and census data it may be necessary to overlay information against other mapped data, for example a thematic map. Get more examples of maps of these different geographies.
Many different variables may be mapped against these areas. For example the population density mapped against districts in the East Midlands. The next UK Census is 27 March 2011.
Global Positioning System (GPS) Data
The Global Positioning System (GPS) has evolved from a navigation system to an important data source for a range of geographical and other applications.
GPS allows positional data to be generated virtually anywhere on the globe under virtually any conditions. An important part of GPS is a constellation of dedicated satellites in orbit around the Earth. GPS receivers are able to estimate time delays in signals from these satellites in order to estimate location (x,y) and height (z) data.
In order to estimate this information, it is also necessary to refer to a model of the Earth’s surface. This model helps in the process of generating geographical data because it helps to determine the coordinate system through which geographical information is expressed. There are many coordinate systems in use around the world, including Great Britain’s National Grid.