Showing posts from March, 2018

North Mull Mesozoic Rocks (3) North of Ardnacross

On the BGS map North Mull and Ardnamurchan, there are a couple of small outcrops of Mesozoic strata just south of Tobermory and north of Ardnacross Farm. These are the rocks that underlie the volcanics. The volcanics are of Palaeocene age ( approx 60 million years old) but the underlying Mesozoic rocks, depending on exactly what they are can be from about 248 million years ago up to 65 million years. So depending on what they are, they could be considerably older

Rocks of this type probably underlie most of Mull but it is only in certain coastal locations (and also as xenoliths and in volcanic vents) that we can readily see them.

This particular outcrop had intrigued me for a while and it was long overdue a visit. Many thanks to Rory Forrester of Ardnacross Farm for letting me explore at leisure!

The view down the sound of Mull is great:

The Sound of Mull looks quite wide at this point. Ben Talla has snow on top as do the hills above Craignure
Its not just the geology - there is a bro…

North Mull Mesozoic Rocks (2) North of Rubha nan Gall

This week's Mesozoic outing was to the area just north of the lighthouse at Rubha nan Gall, just north of Tobermory. This is one of the few places in North Mull where the rocks that underlie the Palaeocene volcanics can be seen. It is easy to get to the lighthouse now as the path has been upgraded. From the lighthouse beyond to where these rocks are takes a bit more effort but nothing too hard.And the views are superb.

I had been to the lighthouse last year. Details are here:

Hopefully not repeating myself this time. Anyway, here are some pics and information about todays walk:

Pictures and details below:

Donations box at the start of the path - still more needed for maintenance

Dont know how I missed this the last time I was here a few weeks ago - a dyke cutting through the lavas. You can see the dyke "side on" a little bit further along the path and I think it may be the same dyke that is se…

North Mull Mesozoic Rocks - the Doirlinn

The Doirlinn (or Doirlinn a'Chailbhe) is the narrow channel between Mull and the Island of Calve, which is well seen from Tobermory. At the lowest of tides, it dries out and you can walk across from mainland Mull to Calve Island. Today at lunchtime was an opportunity to do just that.

As a tidal feature, the Doirlinn is interesting, but the geology also has something neat about it. It is one of only a handful of places in North Mull where the underlying Mesozoic rocks can be seen - Most of North Mull is covered in volcanic rocks, mainly plateau basalts of Paleogene age, cut by numerous minor intrusions (dykes and sills) However in a few places the older rocks on which the basalts have been deposited, the Mesozoic, can be see peeping out. The other places are north of the lighthouse at Rubha nan Gall, south of Tobermory near the Guala Dhubh and north of Tobermory at Bloody Bay, where the rock was once quarried.

I had a good look at this stuff today - below are some photos:

Looking a…