A sinkhole is a natural depression or hole in the Earth's surface which may have various causes. Most natural sinkholes are caused by the chemical dissolution of water-soluble carbonate rocks or gypsum. Sinkholes may vary in size from 1 to 600 m both in diameter and depth. Sinkholes may be formed gradually or by sudden collapse and are found worldwide in ‘karst areas.’
Karst areas are not unique to Nova Scotia; in fact, they occur in over a quarter of the earth’s surface. As a result, there are well-established methods for reducing karst risks. These include actions that can be taken both at the planning and construction stage of a project, as well as on-going actions that reduce the risk of future sinkhole formation.
This dataset was developed to show areas of Nova Scotia where there is a relatively high-medium-low risk of encountering karst and naturally occurring sinkholes caused by soluble bedrock.

This web layer was developed to show areas of Nova Scotia where there is a relative high-, medium- or low-risk of uranium in bedrock water wells. The high-risk zone is defined as bedrock units where more than 15% of well water samples exceed the uranium drinking water guideline of 20 μg/L. In the medium-risk zone, between 5% and 15% of well water samples exceed the guideline and in the low-risk areas less than 5% of well water samples exceed the guideline. The risk zones were developed based on the analysis published in the open file report ‘A Uranium in Well Water Risk Map for Nova Scotia based on Observed Uranium Concentrations in Bedrock Aquifers’: https://novascotia.ca/natr/meb/data/pubs/20ofr01/ofr_me_2020-001.pdf