Clinging to bare rock 10m above the ground, I heard an angry chatter above me. I froze. "Are there any snakes here that sound like birds?" I called down to my guide. At Joshua Tree National Park in Southern California, that question isn't as silly as it might sound. Bigger than Dorset, drier than Syria and often stranger than Australia, Joshua Tree is full of surprises.
The bizarre-looking Joshua trees after which the park is named are not trees at all, but massive, slow-growing yucca plants. Kangaroo rats hop lightly over the hot sand like tiny wallabies while circus beetles perform headstands for amused onlookers – before squirting out a pungently repellent liquid.
And then there are the dangerous creepy-crawlies. Joshua Tree is home to at least three species of venomous rattlesnakes, prone to basking in the desert sun; a tarantula or two; and an aptly named giant hairy scorpion that can grow to 14cm in length. None, my expert guide Susan Cram assured me calmly from below, chirps like quail.
Still, it seemed like a good excuse to pause my ascent and look around. I was one third of the way up a sheer, golden-brown rock called Intersection, one of thousands jutting up from the desert floor. Below me, a sparse forest of Joshua trees rolled out to the horizon, their branches raised like disarmed cowboys reaching for the clear, blue sky. Above me, the foreshortened slope of Intersection seemed to go on for ever, punctuated by shady nooks and the occasional glint of climbing equipment.
Our Intersection route was a fairly easy one, said Susan. On the standard Yosemite Decimal System, it was rated as a 5.6 with a 5.9 start, so theoretically it gets easier as you go. But theory doesn't mean much when the only handhold in sight is just out of reach and an aching foot is losing grip by the second. As a complete beginner to rock climbing, the idea of actually propelling myself up such a cliff seemed incredible.
Susan's company, Uprising, provided all the necessary instruction and safety gear, from harnesses and ropes to helmets and high-traction climbing shoes. All her beginner expeditions are "top roped", a system where climbers are secured by a rope that reaches to the top of the route and then down to a person on the ground who picks up the slack. If this belayer is doing their job, the furthest you can possibly fall is the stretch in the rope, a few centimetres at most.
All the same, it was not something I intended putting to the test. I started my climb at a cautious and deliberate pace, checking my footing over and over again before shifting my weight. And then I slowed right down. Climbers like to say that 80 per cent of climbing happens from the neck up and, for a novice, there are a lot of counter-intuitive practices to absorb. You have to stand up straight rather than hug the rock, press as much weight as possible through even the crumbliest foothold and, above all, trust your belayer completely.
Following Susan's rules, I was surprised to find myself suddenly (if 15 minutes can be considered sudden) far above the ground. My hands and feet seemed to migrate effortlessly from crack to fissure, gripping the rough stone like glue. I could see where I was going and for the first time it actually seemed achievable. Then I slipped.
I doubt anyone but my belayer, Steve, noticed. As promised, I did not so much fall as slump backwards slightly. I found my footing again, looked up to the peak and continued my climb. Intersection, like almost all the rocks at Joshua Tree, is pure monzogranite, a mineral that formed far beneath the Earth's surface tens of millions of years ago. The rocks' fantastical shapes, where smooth boulders seem perched precariously one on top of another, were actually eroded by underground water flows long before ever seeing the light of day.
There are more than 8,000 climbing routes within the National Park, ranging from needle-thin spires to gargantuan boulders. Ask a park ranger what they're called and you'll hear official names such as Wonderland of Rocks, Jumbo and Echo Cove. Ask one of the hundreds of "rock jocks" that flock here to camp and climb for weeks on end, and a different list will emerge.
"Boogers on a Lampshade", "Toto Meets the Bighorn" and "My Balls Feel Like a Pair of Maracas" won't make the tourist maps but they do communicate a flavour of the hundreds of extreme (5.11 and up) climbs on offer.
Low-adrenalin options also abound. There are hiking trails galore and you can camp almost anywhere you want in the park, subject to some common-sense restrictions. Joshua Tree is largely free from light-pollution, making its clear night sky one of the best in the continental US for stargazing. For a taste of the old Wild West, you could try a horse riding tour or a visit to Keys Ranch, a small ghost town within the park that has a well-preserved ranch, school house and shop, littered with rusting mining equipment.
Don't bother hunting for the Joshua tree featured on U2's 1987 album of the same name. Not only was the cover shot hundreds of miles away, the plant itself fell over years ago.
Whatever you do, though, come prepared. Temperatures here can veer from sub-zero at night to scorching sunshine. Carrying plenty of water is essential.
By this point, I had been inching my way up Intersection for about half an hour. My mouth was parched, one of my elbows was bleeding, and I could not have been happier. A few more moves and I reached the top – or at least the flattish ledge that was the top of our climb for the day.
The view over Joshua Tree's alluring, alien landscape was incredible but the feeling of achievement even more so. All that remained was to turn around, lean back almost horizontal and rappel down the face of Intersection.
Rappelling is climbing's way of getting you to come back and do it all again. All the scary moments, grazed fingers and aching limbs are forgotten as you leap out into space and bounce down to earth like James Bond. A high five from Susan and Steve and my rock-climbing career had officially begun.
But I couldn't leave Joshua Tree without driving up to the Key's View lookout to see some of the forces that had shaped its unique beauty. From a windy car park, I leant over a railing to photograph a distant ridge marking the infamous San Andreas fault. A middle-aged woman hovered nervously by her car. "I can't get too close to the edge," she said. "I've got no head for heights." She has no idea.
The closest airport is LA, served non-stop from Heathrow by Air New Zealand (0800 028 4149; airnewzealand.co.uk), American Airlines (0844 499 7300; americanair lines.co.uk), British Airways (0844 493 0787; ba.com), United Airlines (0845 8444 777; unitedair lines.co.uk) and Virgin Atlantic (0844 874 7747; virgin-atlantic.com).
A rental car is the easiest way to get around the park. The main roads are surfaced, but there are unpaved routes to explore, some of which require a four-wheel drive.
Uprising Adventure Guides (001 888 254 6266; uprising.com). offers private tuition from US$215 (£143) for four hours.