From ACT Granite, published by the ANU Mountaineering Club - "Another southern ACT crag discovered by the inimitable Paul Daniel and first climbed during a thunderstorm!  Some good crack and slab routes.  The cliff (GR 734529) is atop a short ridge facing southwest over the upper valley of Rendezvous Creek; it is described here as the only sensible access is from the Lunar Laser Ranger in the Orroral Valley.  From the LLR take an uphill traverse, west-south-west across the slope to the saddle at GR 445538.  (Crossing a spur about 300m down and west from the summit of Mt Orroral.)  Follow a shallow, open valley downwards, crossing the marsh to a group of boulders known as The Atrium (one significant line on the far side, no climbs yet).  Walk through then head parallel to the watercourse to an unprepossessing rise which is the back of the crag.  Excellent camping with running water on tap here.  Overall about one hour (2½km) from the LLR.  Thunder Bluff is a huge boulder up to 60m high bounded on the right by Lightening Slab, a curving sweep of slabs capped by a roof.  Best access to the base of the crag is to scramble down to the southeast end and descend the Helter Skelter Ramp (a carnival slide of leaves and loose rocks) to the bottom of the slab."

Aims

Even though this looks like an aimless wander, there is purpose:

• we first visited Mt Orroral on 20 Aug 05.  Max was kind enough to help me recce my first CBC led walk.  But we didn't climb to the concrete pipe marked top.  On the CBC walk on 22 Oct 05 a fellow walker showed me how to reach the summit, so we both aught to get there this time
• having read the above description in ACT Granite, Thunder Bluff sounds like an interesting objective
• after doing Mt Herlt on 28 Jun 06, I'd like to get to Mt Mavis (SH 1711, E of Big Creamy Flats) sometime soon.  We should get a visual recce from Mt Orroral or Thunder Bluff
• we might be able to attract a tiger walker and pick his brains on other worthy objectives.

Walk

We were away by 7.50am and quickly dispatched the Granite Tops walking track to the Lunar Laser Ranger/Geodetic Observatory (3.9km and 1hr to here).  Took 5 minutes to be blown about and pop on gaiters.

My lessons then began in earnest, the first being to take a B-line to Mt Orroral and not muck about with the ridgeline central saddle or rabbit ears rocks.  Reached Mt Orroral at 9.45am (this leg 1.2km in 55mins) (5.1km and 2hrs to here).  We took our different ways to the concrete marker at the top, holding on grimly as the wind raised towards gale force.  Excellent views.  Down out of the wind for a quick bite of morning tea.  Some changes to the planned route here, as we decided to head straight to Thunder Bluff next, via the hill to the SW of Mt Orroral and clearly visible from the top (pic 1).

The trick, however, was to start heading towards this next objective.  No way directly, so we came off Mt Orroral to the SE until we could bend back to the SW.  Some good granite and a few patches of snow.  Down across the saddle and up the other side, with excellent views back to the W side of Mt Orroral.  Some discussion as we looked back, as to which might be the best route - another option might be to go NW along the Mt Orroral ridge, then off SW from the ridgeline saddle.  Either way, plenty of granite.  The wind had raised its voice to the scream of a jet plane by now.  Reached this feature at 10.40am (this leg 0.66km and 55mins) (5.7km and 2hr 50mins to here).  Stunning views W to the back of Thunder Bluff (as described above, very unprepossessing from this side); the far side of Rendezvous Creek; Mt Namadgi ridge and, on the skyline, snow-dusted Bimberi Peak.  Split Rock was obvious across to the N.

We continued vaguely SW to the back of Thunder Bluff, exiting the scrub at 11.20am onto open granite which just rolled down.  It was difficult to stand in the gale-force wind and impossible (as well as unwise) to approach the edge (this leg 1.2km and 40mins) (6.9km and 3hrs 30mins to here).  Absolutely huge views (pic 2).

We headed SE along the top (pic 3) until we could start to work our way down.  At one point a reasonable sized cave took us down to the next lower terrace.  At last we found ourselves under the side of Thunder Bluff, every inch of 60m high.  The wind was howling above (this leg 0.29km and 20mins) (7.2km and 3hr 50mins to here).

Here we were faced with the decision to either start heading back up and so out via a different part of Mt Orroral, or to go down to Rendezvous Creek and out via 'the saddle'.  I preferred the second option, as that was my original plan.  So down we crashed, traversing to the S and finally hitting Rendezvous Creek at 12.15pm (this leg 0.84km and 35mins) (8km and 4hr 30mins to here).  A perfect place for lunch, out of the wind, in the sun and by the gurgling creek.  And a perfect site for lichen sample collecting (GR7330952226, altitude 1130m).  A 45min energy recharge.

All that remained was to wander a bit more than a kilometre down the creek till we hit the taped footpad up to the saddle, follow it up and across to the Nursery Swamp track and down to the Nursery Swamp car park (this leg 5.7km and 1hr 45mins) (13.8km and 6hr 55mins to here).  Then, a tromp back along the road to the car.

Thanks, Max and Peter, for companionship and advice.  Not a bad little walk.

Distance: 16.8km  Climb: 1000m.  Time: 7.50am - 3.15pm (call it 7.5hrs), with 65mins of stops.