Marine

ITINERARY - See Map 1

Leave St. Andrews by A91 then A92 and the Tay Bridge to Dundee.

Dundee to Perth by A90. This road crosses the flat Carse of Gowrie underlain by late-glacial and post-glacial clays. The Sidlaw Hills to the N. comprise Lower Devonian Old Red Sandstone sediments and interbedded lavas dipping NW into Strathmore, hence the steep scarp slopes facing the road and spectacularly displayed on Kinnoul Hill to the east of Perth.

Cross Strathmore (A9) - surface mainly post-glacial sand and gravel overlying Lower Devonian sediments until Highland Boundary Fault with spectacular fault scarp introducing Dalradian (Precambrian and Lower Palaeozoic) metamorphic rocks with slates and 'grits' (low-grade regional metamorphism) Dunkeld.

Northwards the grade of regional metamorphism increases but much of the ground near the road is covered in glacial and post-glacial 'drift', e.g. hummocky moraine in the area of Drumochter Pass.

At roadcuts high-grade metamorphic rocks of the Moine sequences are intensely folded and cut by pink pegmatite dykes in the region of Dalwhinnie.

From here on past Aviemore fluvioglacial sands and gravels from the last glaciation of the Highlands are widespread over low ground. At Aviemore the Cairngorms to the SE are composed of 'Younger' Caledonian granites (410 my) and form the largest area of ground in Britain over 1200m high. They have been intensely glaciated, e.g. the U-shaped valley of the Lairig Ghru to the SE. 115

High ground occupied by high-grade metamorphics and granite, overlain by late-glacial sediments, extends to 8 km before Inverness.

Field Stop - Getting your field notebook in order!

Inverness lies at the SW corner of the Moray Firth, margined by Devonian sediments unconformably overlying the metamorphic rocks of the Highlands. The sedimentary rocks are softer and more easily weathered, thus giving rise to good arable land, e.g. the Black Isle NW of Inverness. The town also lies on the line of the largest fault in Britain, the Great Glen Fault with a possible strike slip movement of over 100 km. It is still mildly active after a geological history going back for approximately 400 Ma. Glen More (Great Glen) lies along the mile-wide shatter belt of this fault. 145

Cross the Beauly Firth on the Kessock Bridge (A9) to the Black Isle (Middle Devonian sediments) with view to NW to Ben Wyvis (Moine metamorphics). Cross Cromarty Firth to just S of Alness with a fine view of the Northern Highlands (Moine Schists). North-east to Tain. Cross the Dornoch Firth via the new bridge. Continue north to meet the coast at Golspie.

Brora stands near the southern end of a long strip of Mesozoic rocks let down on the Ord fault against Moine Schists and the Helmsdale Granite to the NW.

Beyond the Mesozoic rocks the A9 crosses the Helmsdale Granite back onto Middle Devonian sediments to Latheron. If the weather is clear enough the production platform of the Beatrice Oilfield can be seen offshore (Jurassic reservoir rocks).

A895 (A882) north across part of the largest peat-covered area in Scotland, the 'Flow Country', to Thurso.