Tellus survey plane
Low-flying aircraft will be seen across Kildare in coming weeks and months.
A survey of soil, rocks and water is being carried by the Geological Survey of Ireland (GSI) in Kildare as well as Carlow, Wexford, Kilkenny and Waterford and Wicklow.
The aircraft will fly at a height of 60 metres over rural areas and will rise to 240 metres over towns.
The white twin-propeller plane has a red tail and black stripe.
The GSI said: "The sound is similar to a passing lorry and may startle sensitive livestock such as horses."
The initiative studying geochemical and geophysical data is being funded by the Department of Communications, Climate Action and Environment.
The survey will take place from May until late Autumn and flights are dependent on the weather and subject to change.
The information, which will be made publicly available at a later date, will be used to make new geological maps and manage agricultural, environmental and natural resources.
A freephone number 1800 45 55 65 is available if people have any concerns about sensitive livestock and want to keep informed of flight plans in your area.