(354-290 million years ago)
During this period Britain lay more or less on the Equator and so enjoyed a tropical climate. As global sea levels rose at the start of this period, the former river plains were now flooded to form a shallow sea which extended across much of South Wales. The scene may have been similar to modern-day Florida and the Bahamas with abundant corals growing in warm seas in which brachiopods also thrived.
In time these shallow seas were once again inundated with sand and mud brought down by rivers from the Caledonian mountains to the north. Later the river deltas were colonised by plants and dense swampy forests grew across them.
Towards the end of the period another phase of mountain-building occurred - the 'Variscan Orogeny'. This resulted from the collision, to the south of our area, of the micro-continents of Armorica and Iberica with Laurussia. The major mountain range which resulted began to erode and shed sediments to the north. We see these sediments as the Pennant Sandstones of the South Wales coalfield.
Rocks from the Carboniferous period form spectacular landscapes throughout Britain and do not disappoint in Fforest Fawr Geopark.
For convenience, they can be divided into three layers, the lowermost - the Limestones - being the first to be formed, succeeded by the Millstone Grit then the Coal Measures:
Coal Measures
Millstone Grit series
Carboniferous Limestone Series
Visit the Carboniferous Timechart.
The period is so named because of the large quantities of coal which were formed at that time ('carboniferous' = 'coal-bearing'). Westphalia, Namur and Dinant are regions of western Germany and Belgium which have given their names to subdivisions of the Carboniferous period in the international geological timescale.
this section of the site is still under development - a map of Carboniferous rocks in the Geopark will appear here