The map opposite shows the full area of interest covered by Derbyshire Biological records Centre (DBRC). The boundary of Derby City can be seen in the lower part of the county, mostly falling within the square we define as SK33. Two boundaries are shown. The solid line is liable to change, as it shows the political boundary of modern Derbyshire. The dotted line shows what we call the “Vice-County” of Derbyshire. This is an unchanging boundary, established nearly 150 years ago to help naturalists refer to regions of Britain without having to worry about whether or not they have been altered. Notice how we have both losta and gained parts in the north and north-east, as well as in the south Whilst politicians concern themselves with modern county boundaries, naturalists tend to care more about Vice-counties. Using vice-counties means that species lists made 100 years ago can be compared with those made today. Derby Museum and DBRC need to use use both systems when mapping data or looking after its specimens and displays. The large grid squares are each 10 kilometres across. We call these squares “hectads” Each hectad can be divided into 100 smaller squares, each one kilometre across. We call these single kilometre squares “monads” and these are the same ones that you see represented on Ordnance Survey maps of Britain. Many biological records are submitted to an accuracy of a single monad, although you can always be more specific than that if you wish. A group of four monads is called a “tetrad” - but these tend only to be used by botanists and further explanation would be required to explain how they are used. A series of letters and numbers is used to specific identify points on the map. An explanation of the national grid system will be provided in due course. |
