Marland Yarde scored two tries on a dazzling Test debut as England romped to a first clean sweep in Argentina.
The hosts built an early 12-6 lead in Buenos Aires through the boot of Martin Bustos Moyano.
But two penalty tries and a converted score from Freddie Burns put England 25-12 ahead at half-time.
Wing Yarde's brace and scores from Rob Webber and Kyle Eastmond saw England pull well clear despite replies from Manuel Montero and Tomas Leonardi.
It meant England, who won 32-3 in the first Test, wrapped up their first away series win against the Pumas for 32 years.
After their electric first-half display last week hopes were high the tourists, who were without Lions-bound pair Billy Twelvetrees and Christian Wade, would explode into life once again at the Velez Sarsfield Stadium.
But it was the hosts who started much the better and a combination of their intensity at the breakdown and English ill-discipline gave full-back Bustos Moyano the chance to out-kick Burns at a ratio of two to one to give the Pumas a 12-6 lead after 25 minutes.
Both teams were fielding largely second-string teams, with England having a significant contingent with the Lions and a further handful of established players being rested, while Argentina were without their European-based stars as they took a break ahead of the Rugby Championship later this year.
Argentina had by far the most experienced player on the field in fly-half Felipe Contepomi though, and the former Bristol and Leinster man pulled the strings to perfection in the first half hour before England's pack finally came to life.
They began to dominate the breakdown and scrum and twice in the closing 10 minutes of the half they butchered Argentina at attacking scrums to earn penalty tries.
In between Burns stepped inside the cover to score a try of his own and three conversions from the Gloucester man left the hosts shaking their heads in disbelief as they trotted off trailing 25-12 at the break.
The second half saw more of the same, with Argentina offering the odd threat but finding themselves out-gunned by their youthful visitors, with England's exciting backs looking rapier sharp when presented with the ball.
The Pumas actually scored the first try of the half, though, when Montero, who was later taken off on a stretcher with a leg injury, powered over.
But England soon added their fourth try, hooker Webber dummying and thundering over after a destructive break from Yarde, before the London Irish winger took over scoring duties himself.
His maiden international try saw him beat two men down the touchline. Fifteen minutes later he latched onto Eastmond's crisp inside pass to scythe through untouched.
In between Eastmond got on the scoresheet himself, his percussive footwork taking him past five men to score under the posts.
Argentina managed a second try of their own, number eight Leonardi driving through a forest of bodies to score, but there was only ever going to be one winner as Stuart Lancaster's young guns confirmed England have a bright future.
England head coach Stuart Lancaster said: "Argentina were much improved on last week and put us under pressure so it is even more pleasing to score 50 points. We thought there would be a reaction from Argentina.
"Getting the series win was the first objective. The second objective was to develop our options and looking at other selections and that has been achieved."
Argentina: Bustos; Agulla, Tiesi, Ascarate, Montero; Contepomi, Vergallo; Roan, Garcia Veiga, Bustos Moyano, Farias Cabello, Galarza, Baez, Macome, Leonardi.
Replacements: Gomez Kodela for Bustos (68), Madero for Ascarate (73), Orlando for Montero (67), Cubelli for Vergallo (60), De la Vega for Baez (60).
Not Used: Guidone, Henn, Lozada.
Sin Bin: Bustos Moyano (40).
England: Brown; Wade, Joseph, Eastmond, Yarde; Burns, Dickson, Marler, Webber, Wilson, Launchbury, Attwood, Wood, Kvesic, Morgan.
Replacements: Foden for Brown (64), Myler for Burns (67), Wigglesworth for Dickson (56), Doran-Jones for Marler (67), Paice for Webber (62), Thomas for Wilson (76), Vunipola for Morgan (60), Lawes for Attwood (60)