Archived Environmental Data Discovery Trails – going underground

Welcome to the Digital Trail challenge: Archived Environmental Data Discovery Trails – going underground
May 12, 2024

We have set 5 questions to explore the British Geological Survey’s (BGS) Onshore GeoIndex.

Here's the challenge: You carry out geological surveys for a water well drilling company and are familiar with mapping tools to identify the rocks in an area of interest, but you know that borehole data can provide a lot more information, and you want to discover more.

Need a hint? Throughout the quiz, if you get stuck there are 'hint' buttons to help you.

This quiz is an archive of our event run in August/September 2021. We will not be collecting any feedback or information in relation to this quiz anymore.

Part One - map data

You have been asked to provide the well drillers with the aquifer depth underlying Beaconsfield.
Can you find the relevant borehole data?

To start find the BGS GeoIndex Onshore webpage.

To begin with you need to locate the water-bearing rocks, called aquifers. In the south of England these rocks are mostly the Chalk. Can you find the two bedrock units that underlie (spatially at the surface) the town of Beaconsfield?

Answer format: text in capitals with the names exactly as they are in the legend. Provided in alphabetical order separated by a semicolon and single space, e.g. GAULT FORMATION - MUDSTONE; ZIG ZAG CHALK FORMATION - CHALK

You then want to see what existing data are available in the vicinity of Beaconsfield. Borehole records are a good starting point but what do the different colours of the points on the map mean?

The answer should be text listing the categories separated by a semicolon and single space, e.g. confidential; 25 - 50m; 60m+

Part Two - Borehole Data

Now you’ve got the borehole records, you want to find out something about the geology. The well drillers will need an estimation of the depth to the chalk.

Using the borehole data find out which boreholes reach the top of the chalk. The chalk is at the surface in the northern half of the town but is underneath the Lambeth Group in the south. Using the circle query tool draw a circle south of the red Beaconsfield location pin to narrow down the 29 boreholes in the image. Can you identify which ones reach the top of the chalk?

Answer format: id number of each borehole, eg. SU27NW125 with your resultant list sorted in alpha-numerical order separated by a semicolon and a single space

Great, so we know we have some boreholes that describe how deep the chalk is. But the GeoIndex can give us more data. Next, we can look for digital borehole records, called AGS boreholes. AGS is a new method of storing and transferring borehole data digitally but not everywhere in the country has this type of data yet. Beaconsfield doesn’t have any, but can you find the closest town to Beaconsfield that does have AGS data?

Answer format: text

Because those AGS boreholes are quite far away from our study area we can’t use them, so we need to find other data deposited with the BGS that may contain more borehole records. This data is held in the Deposited Data Layer, usually as points. Add the deposited Data Layer for points. You’ll see there are 2 points in the Beaconsfield circle. One of these points has a digital PDF from which can you find how many boreholes were drilled for this ground investigation?

Answer format: Single integer number, e.g. 5

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