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Meeting at 10.30/45 am on sat May 4th 2024

 

  • The Cave

    Black Burn & Ardclins Pot Caves

 

Type of rock these caves are in and info: 

 

Black Burn Cave is the only known explored, extensive, active cave system developed in Cretaceous Limestones in Ireland. It is probably the most extensive karst drainage system developed in Cretaceous carbonates in the United Kingdom.

 

Black Burn Cave
In normal conditions the stream sinks at the base of a 25m high basalt waterfall, presumably the contact between the Antrim Basalts and the Portrush Chalk Member. The entrance to Black Burn cave lies 110m east of the waterfall and water sinks at this locality in high water conditions. During floods the cave system is too immature to allow all the water to sink at this site and Black Burn carries a stream to the coast.
The current entrance to Black Burn Cave is located at D24622117. This cave has been surveyed for a total length of 142m to date but a further 350m of passage was explored in 1984 by digging through a mobile boulder choke and diving five sumped sections. Black Burn cave can be classified as an epiphreatic cave and in normal conditions the cave carries enough water to prevent entry by cavers.
The passage is controlled by the major joint sets and alternates between sections of vadose and sections of perched phreatic passage. In addition to the entrance series, there are a number of avens which lie on the controlling joints and bring trickle inlets and coarse clastic sediments into the main conduit.
A series of joints are seen in the north and south cliff sides at a narrowing of the gorge 80m downstream from the waterfall and low water river sink. There is a 3m vertical drop in the stream bed at this point. Access to the cave is via a number of the enlarged joints in this area. Flood debris frequently blocks these rifts, restricting access which can only be gained after digging and removing the debris (e.g. logs).
Upstream of the 3m waterfall, an enlarged joint leads to a 4m climb down into a chamber. The joint is known to continue south but is currently choked.
Downstream of the 3m waterfall is another prominent joint through which access to the cave was possible after digging in 1994. This joint though initially horizontal and restricted (1.5m high by 40cm wide), quickly develops into a series of short vertical rifts dropping a total of 12m into a chamber. Three other prominent avens enter the roof of this chamber, the most southerly of which leads back up to the choked joint above the 3m waterfall. In this entrance series of shafts, there are a number of large collapse boulders.
From the entrance pitches the passage follows a southerly trending joint and the vadose nature of the passage changes to phreatic for 15m to a point where the joint control changes from south-southwest to the southeast. Here the passage is a fine phreatic tube with well developed scalloping and a small vadose trench. This leads to an aven chamber after 10m. It is possible to climb up from this chamber into a series of passages heading north towards the gorge.
From this chamber a vadose passage with a notch at stream level follows a southerly trending joint to a point where a small inlet feeds into the main conduit. In very low water this is the first flowing water encountered in the cave. The stream leaves the main conduit 20m downstream at another change in joint control. The passage is significantly widened into a notch at floor level, particularly where basalt cobbles form the passage floor.
The passage now trends northwest, maintaining proportions of 4m high by 1m wide until another aven chamber is encountered. This is the current limit of the survey, the aven being partially filled with basalt boulders which have prevented a continuation of the survey. The location of this point is close to the base of the basalt waterfall on the surface.

The general direction of the unsurveyed passage is northwest and similar in characteristics to the surveyed cave. The phreatic sections during the initial exploration in 1984 held water (five sumped sections). After the first sump, the main stream enters and the passages increase in size. The vadose sections between the sumps reach a maximum of 6m by 2m, significantly larger than in the surveyed section of cave. There is also a significant loss of height in this section, including a 4m waterfall. Exploration was halted at the fourth sump (sump 5 in all) in the Main Stream Passage.

 

The Cretaceous (IPA: /krɪˈteɪʃəs/ krih-TAY-shəs)[2] is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation Kreide.

The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was largely ice-free, although there is some evidence of brief periods of glaciation during the cooler first half, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth by the end of the Cretaceous, coincident with the decline and extinction of previously widespread gymnosperm groups.

The Cretaceous (along with the Mesozoic) ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out, widely thought to have been caused by the impact of a large asteroid that formed the Chicxulub crater in the Gulf of Mexico. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary (K–Pg boundary), a geologic signature associated with the mass extinction that lies between the Mesozoic and Cenozoic Eras.

 

1st Black Burn,Ardclinis Pot & Area - Sat May 4th *Day Trip*

£5.00Price
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