Allt Mor
Geological Conservation Review site | GCR #2221 | Geomorphology | Fluvial Geomorphology of Scotland
Scotland's geosites are chosen because of their local, national or international importance. Take only photos, leave only footprints: avoid causing any damage to this site. You can walk almost anywhere in Scotland without the need to ask permission or keep to paths, but you have a responsibility to care for your own safety, to respect people's privacy and peace of mind and to cause no damage.
This site is a Site of Special Scientific Interest (SSSI). It is an offence to intentionally or recklessly damage the protected natural features of a SSSI, and this includes unauthorised sample collection.
The right of access does not extend to quarries, building sites or any land where public access is prohibited, or to the collection of geological samples.
Summary
The Allt Mor is an excellent example of a steep mountain torrent whose planform adjustment over the last 40 years has been reconstructed. In terms of slope, sediment supply, sediment size and degree of channel confinement, the river system can be subdivided into three very different but interrelated sub-systems. The headwaters are relatively stable, with limited sediment supply due to the proximity of the drift-bedrock boundary. Within the middle gullied section, the river has entrenched deeply into glacial and fluvioglacial deposits producing a restricted active area but with an unlimited sediment supply. This is important in comparison with other systems where sediment supply is more limited. Downstream where channel slope decreases and the potentially active area widens, a large, periodically active gravel fan has formed, with sediment size ranging from coarse boulders to fine sand. This system is particularly interesting in its response to periodic flash floods, with material being flushed out of the gully section and deposited downstream on the fan.
Site information
Access
The site is very close to the Glenmore Lodge outdoor centre and is readily accessible from a network of forest trails. There are several car parks along the road up to the Cairngorm ski centre.
Further information
https://www.geograph.org.uk/photo/1263148
Another view of bank erosion.
https://www.geograph.org.uk/photo/6150096
Extremely large boulders only move in serious floods.
https://www.geograph.org.uk/photo/776398
The Coronation Bridge.
https://www.geograph.org.uk/photo/6150115
The active alluvial fan. Good imbrication in the boulders.
Related geosites
Overlaps with:
Carol Pudsey
June 4, 2022
Oblique satellite image of the lower part of the Allt Mor, looking upstream. The palaeofan occupies most of the lower ground below the footbridge (arrowed) while the active alluvial fan lies within the red ellipse. Image © 2025 Google Earth.
Carol Pudsey
June 4, 2022
Oblique satellite image of example of slope failure in thick drift deposits.