20m beyond (west of) the 3m ladder climb in Tirolia Werke is a small opening low down in the left hand (south) wall. This is the entrance to Gravel Pit, so named because most of the walls, floors and roof are made of pebbles stuck together with mud. The small hole opens into a large space, which is a pitch, split by a ledge 7m down. Below this, the pitch turns into a steep (still roped) slope.
At the foot of the rope (c18m) is a chamber with a steeply sloping loose silt floor. Looking downslope (south) a dry streambed runs down right (NW) to left (SE). Upstream (right) leads to an easily diggable (in sand) small hole, from which a strong draught issues [C1997-161-01 B]. The passage appears to slope upwards beyond the dig, and is heading back under Tirolia Werke.
Left at the foot of the slope, beyond a boulder bridged over the streambed, leads to a 5m pitch with one bolt on the right hand wall/ceiling. A tiny hole in the wall here leads into a washed-out boulder choke. A large (after rain in Austria this was normal Swildon's sized) stream bubbles out of a sump and courses down through the boulders, to a wet slot.
Above the sump is a continuing rift which needs to be climbed into and therefore has not been pushed [C1996-161-90 C]. There is a suspicion that it would go to Elin Algor, possibly at [C1996-161-78]. However, from the survey, this would appear to be well beyond the end of Elin Algor, possibly heading towards the unexplored area between Kaninchenhöhle and the southern Schwarzmooskogel systems.
The stream from the sump can be followed steeply for about 20m to a tight squeeze [C1996-161-89 B] pushed in drier conditions in 1997. It continues down a very small flat-out passage (that appears to flood to the roof in places) through squeezes to another tight squeeze that enters five metres of walking passage. This is short-lived, leading to a down slope and extremely awkward slot. After negotiating the slot you land on soft mud that quickly ends in a low sump. On turning back another low passage can be seen to the right of the original passage. This is a flat-out wriggle with squeezes to a boulder collapse 30m along (the passage has to be reversed out of). This series has been sketched but not properly surveyed, and has nothing to commend it. It should be avoided except in the driest of conditions.
Back at the bottom of the first pitch into Gravel Pit, across the steep slope to the east (care!), a small canyon in the gravel leads through a broader hading rift to an awkward 2m scramble down. This brings you out over the head of a 8m pitch with a very loose takeoff. It is possible to traverse round to the left at the pitch head to a climb down taking one 5m above the stream. Looking across the pitch-head, another gravelly passage (apparently walking sized) can be seen continuing on the right [C1997-161-02 A]. This would be very hard to gain access to due to the gravel walls and overhanging gravel pit.
The pitch is descended by spits in the 'large' boulder embedded in the gravel to the left. A small stream is followed for 30m down a few climbs to a large aven. The stream disappears into rubble but can be regained the other side of the chamber but then rapidly disappears into a small mud hole that looks like it floods in wet conditions. Several holes in the roof become too small very quickly.
There are two very large holes at the apparent top of the Hall of the Mounting Choss boulder slope. The leftmost of these [C1996-161-75 A] has been descended to a ledge with an undescended continuation visible. The right hand hole from Hall of the Mounting Choss [C1996-161-74 C] appears in fact to be the same pitch. A description of the left hand route follows.
Two bolts in the left hand wall of the chamber provide a short, scrappy descent to a large sloping boulder-strewn ledge where a further bolt affords protection for the descent across the ledge (whilst avoiding a rub further up). Just below the lip of the ledge is a rebelay, where good footholds assist its passing. From here the floor can be seen some 20m down. Two further rebelays are required to complete the descent, both of which are bolted as all of the available naturals are insecurely attached.
The foot of the pitch is spacious, some 5m across; to the left (facing the rope) is a descent round to the left, passing beneath a very large wedged boulder high up in the rift, to the foot of an impressive aven, which is assumed to be the other pitch from that corner of Hall of the Mounting Choss. To the right from the foot of the pitch is a hole down through boulders, too tight and unstable to enter, down which stones fall free for over 3s. There initially appears to be no viable way on from here, but in an alcove at the foot of the pitch is a crawl concealed behind a flake on the right. This is initially flat out, but almost immediately eases and reaches a left turn and, straight ahead, a climb down into a small chamber.
This chamber has a narrow slot in the floor which seems to communicate with the deep pitch beneath the boulders mentioned above. Back in the crawl, the left turn leads to an easy continuation which soon develops a narrow floor slot; after some 10 or 15m the floor abruptly ends and one is left with head and shoulders poking out of the crawl overlooking an impressive rift. Stones fall for 3s before first impact, then fall free again before rattling away. The sound of running water can be clearly heard throughout this part of the cave, which unfortunately remains unsurveyed.