Last Night's TV - Geordie Finishing School for Girls, BBC3; Richard Hammond's Journey to the Bottom of the Ocean, BBC1

Tyne travellers are on another planet

You get a choice of Geordie stereotypes on a Tuesday evening now. On MTV, Geordie Shore continues in its mission of depicting the city's young people as airheaded hedonists with the sexual decorum of bonobo chimps, while on BBC3, Geordie Finishing School for Girls prefers to emphasise the single-mother, benefit survivor aspect of things. In fact, you don't even have to choose, since the BBC programme is on at 9pm and MTV's contribution to inter-community understanding at 10pm. So, if you're a real glutton for punishment, you can spend two straight hours on Tyneside, segueing from gritty underbelly to Bigg Market lairiness without a break. You will notice a change of texture though because while MTV does everything in its power to exaggerate caricature, Geordie Finishing School for Girls is at least notionally in the business of overturning prejudice.

The conceit is a head-on collision of received opinions. Four pampered young southern girls, most of whom have banker daddies or some other form of human cashpoint, have been sent to spend time with four Geordie lasses from working-class families. The southerners are supposed to think the northerners will all be as rough as a goat's knee, while the northerners are meant to think the southerners will be stuck-up and spoilt. Whether they genuinely feel this reciprocal contempt I don't know, but they obligingly supply soundbites here to work up the prospect of conflict. "Lazy buggers... get off your arse and go to work," said one of the posh girls, summarising her nuanced view of those on welfare benefits. "Ah think they'll shit thurselves," said Kimberley, asked to forecast the reaction of the visitors to living in one of Newcastle's poorer areas.

The go-between for their encounters is Huffty, who you may remember as a bit of northern grit on The Word, but who has now matured into a rockabilly social worker. Huffty is the personification of local pride, full of talk about Geordie warmth and friendliness but not so blind to the counter-examples that she doesn't take the southerners' jewellery into protective custody as soon as they arrive. In return, she hands over £59 each for the next 10 days, the equivalent of job seeker's allowance minus some deductions for rent. "How long would that last you in London?" she asked. "About two days," lied Lucy.

Out on the streets, Steph (politics student, keen rower) was wandering around like a prospective Tory candidate. "The area is absolutely charming and I haven't seen any sign of poverty yet," she gushed. She was just as effusive about Kimberley's house: "It's very rare to find three generations living under one roof, but in terms of society there couldn't be anything more healthy because it just breeds a family spirit and that's delightful."

The toffs were then taken off for a reverse elocution lesson, tackling elementary Geordie vowels and some trickier bits of vocabulary, such as the "furter copiyah", a device used on Tyneside for making facsimiles of documents (or, if you've had a very lively night, intimate portraits of one's own genitals). They sniffed suspiciously at northern delicacies like pease pudding and went to a pub on match day to meet the Toon Army. And then they were made to cry, after being sent round to Natalie's council house to paint her bathroom and listen to tales of drug addiction, prostitution and infected needle marks. Somewhat to the producer's disappointment, I suspect, everyone from both sides behaved very well, which is perhaps why they're all going to be given masses to drink in next week's episode in the hope that something finally kicks off.

Richard Hammond's Journey to the Bottom of the Ocean is one of those television pop-up books, in which the shortcomings of the natural world – when it comes to attainable spectacle – are compensated for by computer graphics. It's full of pull-the-tag and lift-the-flap moments, during which the mechanics of plate tectonics are diagrammed or the contours of the sea bed revealed. To reveal the inner workings of the planet, Hammond tells us, the BBC has constructed a virtual Earth, seen here as a massive globe levitating mysteriously inside what looks like an airship hangar. Hammond occasionally climbs into a cherry-picker and levitates himself towards some detail, eyes glazed with wonder at what was presumably dusty thin air before all the green screen work was done.

For about 20 minutes of its length, it's quite engrossing. Hammond dived into a tectonic rift in Iceland (which will have been nice for the people who missed the same sight in Earth: the Power of the Planet, a few years ago), and he showed us astonishing footage of sulphur mining in the Kawah Ijen volcano in Indonesia (which will have been nice for the people who missed it when it was shown on The Human Planet just a few months ago). He also, most intriguingly of all, talked to a marine biologist about a snail that absorbs so much metal from deep ocean vents that it ends up with an armour plate shell. Unfortunately, though, the 20 minutes of interesting stuff is dispersed throughout the programme and interleaved with the deep tedium of Discovery Channel bombast, a rhetorical form that is so clogged with superlatives and worked-up awe that it leaves you aching for a bit of human nuance and ambiguity.