Leaders: Dr Chris Burton & Dr Jim MacDonald
This complex, close to the head of Loch Lomond, together with the Arrochar Igneous Complex forms part of a group of post-orogenic intrusions known as the South Grampians Suite, which were intruded into the Southern Highland Group during the mid-Silurian (ca 425 Ma). The rocks of the complex are dominantly dioritic and high in potassium, but with an extraordinary petrological range from ultrabasic picrites to acid granodiorites, this wide range being the result of magmas derived, unusually, from not one but several parental lithologies, including both crustal and mantle types.
The excursion will be confined to the area immediately to the east of the Garabal Fault, between Lochan Beinn Damhain and Garabal Hill itself. Here picrites, gabbros, hornblendites and a range of pyroxene-rich diorites and granodiorites and the relationships between them can be seen, all under the thermally-metamorphosed roof of the intrusion.
NB: The area is accessed from the A82 near Beinglas Farm along a relatively easy but fairly long ATV track followed by a short hill-traverse. The distance from the A82 is ca 4.6 km (2.85 miles). There will be some rough terrain on Garabal Hill itself. Given the distances, the excursion will be a long one and will require an 8 am start.
Leaving Gregory Building at 8:00, travelling by coach
£15 deposit. This is set at a level to recover the anticipated costs of the trip. In addition, please be aware that any balance of costs will be recovered by a small surcharge on the day of the excursion.