White Heat, by Dominic SandbrookSeventies, by Howard Sounes

Children of the revolution?

A "decade" is conventionally defined as a period spanning 10 years, and the temptation for political and cultural historians to regard each specific 120-month block as a discrete era, with its own unique characteristics and atmosphere, has traditionally proved hard to resist. Unfortunately, history is incapable of colouring in the big picture without scribbling over the lines. A recognisable and definable era may often refuse to conform to the inflexible confines of the decade grid.

Hence the notion of the "Long Sixties", a period commencing sometime during the late 1950s and stretching well into the 1970s. Dominic Sandbrook, a young historian born in 1974, takes this long road. White Heat, his "history of Britain in the Swinging Sixties", picks up the story in 1964 where his previous work, Never Had It So Good, left off. A third book covering the 1970s is in the pipeline, making the case that the distinct era under his microscope is not an individual decade but the full quarter-century that stretches from 1956 - the year of Suez, which he covers in serious detail, and Hungary, which his parochial tunnel vision causes him to mention in passing - to Margaret Thatcher's accession in 1979, which changed the game.

This makes sense. Despite the immense social and cultural upheavals of that era - which Sandbrook's mild fogeyism causes him to downplay at every turn - the consensus dubbed "Buttskellism" in its first phase, and summarised by The Beatles as "Ha ha Mr Wilson, ha ha Mr Heath", remained intact. The 1970s were the 1960s continued by other means: a sequel rather than a new movie. The era that succeeded was the "Long Eighties", and it's still going on.

As Sandbrook points out, he is the first chronicler to tackle this era without having lived through it, which he sees as a guarantor of historical objectivity. In the preface to this book's predecessor, he primly reproves earlier writers who "found it hard to separate their own private memories from their interpretation of the subject". He therefore positions himself as the Hoodie Historian, slouching into shot while throwing whatever passes for gang signs in the history department of the University of Sheffield, and announcing to Arthur Marwick, Jonathon Green et al that "You is all mi bitches nuh."

In practice, Sandbrook has a very definite agenda. Without descending to the reactionary hysteria of Christopher Booker's The Neophiliacs - a work it is impossible to reread without wondering how God managed to restrain Himself from burning our blasphemous planet to a cinder - his purpose is to rubbish the counter-cultural view of the era by pointing out that the entire nation did not spend the period tripping naked in Hyde Park listening to The Rolling Stones. Decent, sensible Normal Life went on throughout it all.

This staggering revelation, that the Long Sixties was a time of dialectic wherein the thesis of conventional British life met the antithesis of radical new culture, politics and lifestyle, and thereby produced the synthesis that most people inhabited, has been researched with commendable diligence. It is presented with a puppyish pride that is almost endearing. Almost as endearing, in fact, as the book's finest evocation: the lurching, drunken figure of George Brown, Harold Wilson's deputy, who stumbles through the narrative like some mythic harbinger of chaos, leaving destruction and turmoil in his wake.

Howard Sounes, on the other hand, sedulously sticks to the grid. Seventies, subtitled "the sights and sounds of a brilliant decade", begins in January 1970 with the filming of Bob Rafelson's Five Easy Pieces. It closes with Andy Warhol going to work at The Factory on 1 January 1980, after Woody Allen's New Year's Eve party. In between is a thoroughgoing, if literal-minded, attempt to rehabilitate a much-maligned era, damned through endless jokey, superficial clip shows as an awful litany of naffness: bad hair, tacky pop, tragic clothes, cheap confectionery.

To this end, he has produced his own clip show. Alighting on islands of excellence, ranging from architecture, literature and photography to rock, film and cartoon, he aims to demonstrate that "the decade that taste forgot" was not crap but fab. It's difficult to quibble with his selections. His library shelves groan with Iris Murdoch, Alexander Solzhenitsyn, Norman Mailer; his art gallery displays work by Gilbert & George, Andy Warhol, David Hockney; his rock stage showcases David Bowie, Bob Marley, Stevie Wonder, The Sex Pistols; on his big and small screens we find Apocalypse Now, Jaws, The Godfather, Monty Python.

Nevertheless, we have a few problems, Houston. The first is that every era has its good, its bad and its ugly, and this is not a unique characteristic of the Seventies. The second is that Sounes is frequently overwhelmed by his own powers as a researcher, and the result is an excess of info-dump. The third is that the eclecticism results in some jarring transitions. The outcome is that the dots are rarely joined, and the context for all the fabulosity Sounes celebrates is barely sketched.

In Down The Highway, his life of Bob Dylan, Sounes demonstrated both that his analysis of Dylan's art and its place in cultural history is unlikely to cause Greil Marcus or Michael Gray many sleepless nights. Seventies shows him grappling with full-on cultural history, but it rarely transcends its objective of serving as an antidote to the reductive view of the era. It is effective enough, but of limited value to anyone whose existing knowledge of the period goes beyond Abba and Spacehoppers.

What both books have in common, apart from eerily similar cover designs, is the sense that the departed era of the Long Sixties still extends too many tendrils into our own epoch to be neatly dissected and dispatched to any sealed display case. Forget it, guys: it's Chinatown.

Charles Shaar Murray's 'Crosstown Traffic: Jimi Hendrix and Post-war Pop' is published by Faber & Faber