A Bit of Gray on an Emerald Isle

Though Ireland is known for the many shades of green that grace its grassy pastoral landscapes, there's one corner of the Emerald Isle where gray reigns supreme. In the Burren region, on the island's west coast, what geologists describe as limestone pavement covers much of the rocky, treeless landscape.

The OLI (Operational Land Imager) on Landsat 8 captured this view of the Burren on May 16, 2025. The fossil-rich limestone that makes up the gray outcrops was deposited about 325 million years ago during the Carboniferous Period, when what is now Ireland lay near the equator beneath warm, shallow seas. Although the limestone was initially deposited in flat, horizontal layers on the seafloor, it later buckled into gentle arch- and trough-shaped folds as tectonic plates collided during a mountain-building episode known as the Variscan Orogeny.

These folds in the tilted rock layers and differences in their rate of erosion produced the terraced appearance that defines the Burren's hills, with more erosion-resistant layers of rock persisting as ledges. Glacial activity also played a role in sculpting the landscape, scraping away soil and sediment to expose the limestone pavement and smoothing the region's hills.