Graham Eaton / A glacial erratic of Silurian age sandstone, perched upon younger Carboniferous age limestones. The limestone forms a limestone pavement with the hill , Whernside, Yorkshire, England, UK.

Graham Eaton / Glacial erratic of Silurian age sandstone, perched upon youger Carboniferous age limestones. The limestones form a limestone pavement with the hill Ingleborough in the background. Whernside, Yorkshire...

Graham Eaton / An erratic of Silurian sandstone sitting on Carboniferous limestone at Twistleton Scar above Ingleton, with Ingleborough in the backgrond, October. Whernside, Yorkshire, England, UK.

Will Watson / Erratic boulder deposited beside Llansgorse Lake during the last Ice-Age, an Intraformational conglomerate from the Old Red Sandstone Succession, Devonian Period, and drystone wall, Brecon Beacons Nat...

Graham Eaton / A Glacial Erratic at Norber near Austwick, Yorkshire, UK. This is one of the Norber erratics, where blocks of older Silurian sandstone were left on top of younger Carboniferous limestone by a retreati...

Graham Eaton / A Glacial Erratic at Norber near Austwick, Yorkshire, UK. This is one of the Norber erratics, where blocks of older Silurian sandstone were left on top of younger Carboniferous limestone by a retreati...

Graham Eaton / A Glacial Erratic at Norber near Austwick, Yorkshire, UK. This is one of the Norber erratics, where blocks of older Silurian sandstone were left on top of younger Carboniferous limestone by a retreati...

Graham Eaton / Glacial Erratics or boulders transported on top of a glacier, Iceland, March. After the ice melts or retreats, such erratics can be deposited many miles from thier outcrop.

Nick Hawkins / Glacial erratic and milky way, photographed on Borgle's Island, Nova Scotia, Canada, September.

Nick Hawkins / Glacial erratic, boulders transported by melting glaciers, photographed on Borgle's Island, Nova Scotia, Canada, September.

Nick Hawkins / Glacial erratic, boulders transported by melting glaciers, photographed on Borgle's Island, Nova Scotia, Canada, September.

Graham Eaton / A glacial erratic dropped by ice during the last glaciation is perched on top of a Roche Moutonnee (Sheep rock) that was carved by ice. Cadair Idris, Dolgellau, Wales April 2014

John Cancalosi / Glacial erratic stone made from quartz and basalt, UK, January.

Orsolya Haarberg / Glacial erratic rock on mountain side, Steinsundoey Island, Solund, Sogn og Fjordane, Norway. June 2012.

Orsolya Haarberg / Mount Nammatj and Tjakkeli, viewed from Ritok in winter, Rapadalen, Sarek National Park, World Heritage Laponia, Swedish Lapland, Sweden. April 2014.

Jouan Rius / Jeffrey pine (Pinus jeffreyi) and glacial erratic boulder, Yosemite National Park, California, USA, October 2012.

Jouan Rius / Jeffrey pine (Pinus jeffreyi) and glacial erratic boulder, Yosemite National Park, California, USA, October 2012.

Jouan Rius / Jeffrey pine (Pinus jeffreyi) and glacial erratic boulder, Yosemite National Park, California, USA, October 2012.

Sandra Bartocha / Erratic boulder on the shore of the Baltic Sea, Jasmund National Park, Germany, October

Ben Hall / 2020VISION / Dusk over upland moorland landscape, with erratic boulder in foreground, Lake District NP, Cumbria, England, UK, November

Bryan and Cherry Alexander / Shattered glacial erratic resting in a smooth glacially eroded landscape. Blomstrand, Spitsbergen, Svalbard, Norway, June 2008.

Bryan and Cherry Alexander / Glacial erratic resting on the tundra at Blomstrandhalvoya with Purple saxifrage (Saxifraga oppositifolia) flowers nearby. Spitsbergen, Svalbard, Norway, June 2008.

Graham Eaton / A 'glacial erratic' or boulder deposited by retreating ice, outside Cwm Idwal, Snowdonia National Park, Wales, January 2009

John Waters / Glacial erratic boulder, in limestone landscape, The Burren, Country Clare, Republic of Ireland.

Niall Benvie / Rocks left by glacier movement - glacial erratic, in a lake-side bog, May, Songli, Sør-Trøndelag, Norway

Yva Momatiuk & John Eastcott / Glacier receding over golden tundra slope, with grasses, lichen, moss, rocks and erratic boulders, fall morning, Salversen Range, Smaaland Cove, South Georgia Island, Southern Ocean, Antarctic Converg...

Yva Momatiuk & John Eastcott / Blue glacier receding and small tarn or pond, on green and golden tundra slope, with grasses, lichen, moss, rocks and erratic boulders, fall morning, Salversen Range, Smaaland Cove, South Georgia Isla...

Doug Wechsler / Rock left by glacier movement - glacial erratic, Yellowstone National Park, Wyoming, USA

Philippe Clement / Kettle pond and erratic boulder (glacial features) on tundra, Denali NP, Alaska, USA

Philippe Clement / Glacial erratic boulder, remnant of the last ice age, Yellowstone National Park, Wyoming, USA.

Jason Smalley / Erratic boulders on limestone pavement, Yorkshire Dales, above Ingleton, England

Ashley Cooper / The Norber Erratics, glacial deposits of Silurian greywacke sandstone rock, perched on top of limestone, Austwick, Yorkshire Dales National Park, Yorkshire, UK. July, 2020.

Ashley Cooper / The Cheese Press stone, two huge limestone boulders, Kingsdale, Yorkshire Dales National Park, Yorkshire, UK. August, 2020.

Ashley Cooper / The Cheese Press stone, two huge limestone boulders, Kingsdale, Yorkshire Dales National Park, Yorkshire, UK. August, 2020.

Ashley Cooper / The Norber Erratics, glacial deposits of Silurian greywacke sandstone rock, perched on top of limestone, Austwick, Yorkshire Dales National Park, Yorkshire, UK. July, 2020

David Fleetham / Harlequin / Clown / Many spotted sweetlips fish (Plectorhinchus chaetodonoides) swims in erratic pattern mimicking spanish dancer nudibranch to deter predators, Celebes sea, Mabul Island, Malaysia.

Will Watson / The Whetstone on Hergest Ridge, a glacial erratic boulder, composed of gabbro, Herefordshire, England, UK. October.

Will Watson / The Whetstone on Hergest Ridge, a glacial erratic boulder, composed of gabbro, Herefordshire, England, November.

Graham Eaton / Glacial erratic at the side of track in mountains. Zermatt, Valais, Switzerland. September 2019.