Linn Park et alia loca
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Geology

Linn Park has an amazing geological history, as has been recognised by many organiasations, least of the Linn Park Gentlemen's Walking Club: who else goes home with a piece of coal ?

The Geological Society of Glasgow comments:

Linn Park is one of Glasgow’s hidden gems – a deep rocky gorge and an impressive waterfall tucked away in the busy southside suburbs. The rocks tell a story of Glasgow’s long distant past, many millions of years ago, when volcanoes and tropical coal-swamps dominated the landscape. The gorge was carved through the tough rocks by the White Cart river (merely thousands of years ago!) when it was swollen by melt water from the Ice Age glaciers. Water and coal have since powered Glasgow’s industrial revolution and if you look carefully you can still find traces of it in the woods and river banks, slowly being reclaimed by Nature.

Another comment from the British Geological Survey in 2013 reads:

Along the picturesque river in Linn Park, sedimentary rocks of the Carboniferous age Limestone Coal Formation can be seen.

At Linn Waterfall, the sedimentary rocks have been intruded by a resistant microgabbro sill which forms the waterfall that gives the park its name. Hexagonal columns can be seen in the sill at the falls, similar to the columns at the Giant’s Causeway in Northern Ireland.

Downstream of the waterfall the river runs in a deep gorge. Landslips along the gorge walls indicate that the steep gorge is unstable but also produce good exposures of the sandstones and siltstones that were once deposited by ancient rivers - rock fall at Millholm.

The British Geological Survey Report for Glasgow has three reference points in Linn Park, namely

  • Court Knowe [Ref Point: 17]
  • The Waterfall [Ref Point: 9]
  • White Cart Water, Holmwood House [Ref Point: 8]

An overview by Stuart Nisbet:

The landscape of the area has been shaped by the most recent glaciation which ended 12,000 years ago. The underlying rocks date from the Carboniferous age (310 – 350 Million years old). They have been exposed through the erosive power of the White Cart and its contributing burns. Some have also been exposed by man (by quarrying and mining).

In Linn Park and Netherton Braes, we can see rocks from three main stages of the Carboniferous period [oldest first]:

  • Viséan (Lower Carboniferous), c.350 to 330 Ma. These occur later, when lavas were intruded into the local strata, notably forming Linn Waterfall.
  • Namurian (Upper Carboniferous), c.330 and 310 Ma. Almost all of the rocks in the area are from this period (Limestone Coal Formation and Upper Limestone Formation).
  • Westphalian (Upper Carboniferous to Early Permian), c.310 to 300 Million years ago. These outcrop in the valley of the Kittoch Water, at the upper end of Netherton Braes, near where the Kittoch meets the White Cart, opposite Overlee Park.

Index Limestone

Within the Namurian period, the Index Limestone forms the boundary between the Limestone Coal Group and Upper Limestone Group. This limestone was formed from the shells of billions of marine creatures which settled out of a shallow sea. The shells of these creatures can still be found today, fossilised in the limestone. The Index limestone outcrops generally down the west side of the Cart, thus rocks to the west of the Cart are from the Upper Limestone Group and to the east, from the Limestone Coal Group.

Limestone Coal Formation

When the Limestone Coal Group was laid down, Britain lay much further to the south than today, approximately on the equator. The area which now comprises Central Scotland was part of a large tropical delta, similar to the Amazon delta today. Most of the time the area was flooded by the river and sediments were laid down which formed sandstones and shales.

Over long periods of time the level of the land gradually rose and fell in a cyclic fashion. When the land rose high enough in the estuary for plants to grow, tropical forests developed. The decay and subsequent burial of these forests resulted in the formation of the coal seams in this area.

Upper Limestone Formation

In the Upper Limestone Group, flooding by the sea was a more common event and limestones are more frequent than coals. The periods which formed these economic minerals were relatively infrequent events. Thus the limestones and coals represent only a small percentage of the strata in the area. The bulk of the rocks are sandstone and shale.