Blackrock Cave was discovered in 1988 when a small team ventured northwards beyond Imperial Cave, the previous limit of exploration. After seeing the telltale sign of a draught, they scrambled up scree and onto a small ledge which led to a very small entrance; this gave no hint of the vast system beyond. Squeezes and climbs led up to a slightly bigger passage which emerged in the cliff face. In the opposite direction a flat out crawl through a calcited bedding led to much larger well decorated passages, heading further into the mountain. The scale of the cave continued to grow, with pits in the floor and a pitch to a streamway. A five-way junction (Milliways) was reached and this formed the main bivouac site for the exploration of the cave.

Blackrock’s passages are strike controlled, generally following a 30º alignment and looping between beds to form long passages running in parallel. From Milliways, the main route into the mountain heads southwards through the Flower Shop, a dry sediment-filled passage with a floor covered in gypsum crystals and an impressive display of flat, wing shaped, stalactites which are aligned with the draft. This section of the cave eventually loops round through 180º to enter the Blowpipe, an impressive 30m high by 15m wide passage displaying stalactites and stalagmite bosses.

Wing Shaped Stalactites in the Flower Shop | Matt Kirby

After a short, bouldery section, which crosses the bedding, the main route breaks out into the impressive Rudang Gallery - the most significant section of the cave ­ with proportions that are truly breathtaking. At 3.7km in length (most of which is never less than 30m wide by 30m high) it has formed one of the major trunk routes through the mountain. Southwards leads over mud banks to the Eagle’s Ramp, an awe-inspiring slope of boulders which heads upwards for 135m at an angle of 43º, ending at a blank wall with only a small hole in the roof as a hint of things to come. At the base of the ramp a side passage leads down to a tee junction with a streamway, the upper continuation of the Clearwater River. This is a dark and gloomy area where evidence of major flooding and backing up of water extends into Rudang Gallery, the cause of the mud deposits which make progress very difficult. Downstream, the streamway soon enters a bouldery chamber containing an inevitable downstream sump.

Northwards in Rudang Gallery is a pleasant stroll over sandy sediment banks with a wide sweeping arched roof; a surveyor’s dream.

Firecracker River Passage | Jerry Wooldridge

At a t-junction on a loop in the passage a small streamway is met. This is the Firecracker River, a small modern-day stream which takes marginal drainage from the alluvial plain and has nothing to do with the original development of the passage. The stream heads north to disappear into the Black Silk sump.

From the t-junction, the main route is known as Firecracker but in reality it is a continuation of Rudang Gallery. For the explorers, this formed the most incredible section of surveying, with seventy consecutive 30m tape lengths recorded; if only they had had a 50m tape, life would have been much easier! Firecracker is of immense proportions, 50m high and 40m wide with tall avens leading upwards and water falling from high above. Inaccessible avens and passages were seen high on ledges and were noted as possible leads for the future. The main passage runs for 2.2km in a straight line and ends at Guy Fawkes’ Chamber, a heavily calcited area which is very close to the surface.

Half way along Firecracker is a major junction. This leads to the Racer Series, which is of similar proportions to Firecracker. Smaller passages lead off westwards eventually choking near the surface but the main route passes through large boulder-filled chambers to an awkward upward climb that leads back to the surface at the Racer entrance.

The Racer Series | Jerry Wooldridge

All the 1988 discoveries were made on the same horizon, which was effectively at base level. During 1989 a small upper series (Phoenix) was discovered after ramps off the Flower Shop were scaled. This area is very well decorated and close to the surface. Impressive shafts lead back down to base level but a small passage which was left in ’89 was pushed further in ’91 and led to a connection into Clearwater Cave’s West Passage. Another steep, bouldery ramp led down to base level but a hole half way up the wall was noted and this subsequently led into Sceptic Scenic’s Series in Leopard Cave.

Although Blackrock had been a significant discovery, which filled in a large blank on the map, it was always suspected that something must lie above it. Over successive expeditions, the teams had made considerable efforts to gain access to horizontal passage development at a higher level but all leads were vertical, heading out of the roofs of the major passages and therefore almost impossible to access. Phoenix had been a success but this had been very difficult and had led to only a small isolated section. To attempt to scale the many avens in Blackrock, in the hope of finding something, would have been a major logistical undertaking.

The only leads in Blackrock were out of reach and so the focus of exploration moved to Hidden Valley; the secrets of Blackrock’s upper series were left for future explorers.