It was one of four lorries involved in a collision on the motorway in Bedfordshire between junctions 12 and 13 at about 07:00 GMT.
Highways England said the jam had been cleared up and all southbound lanes had now reopened.
However, it warned of continuing delays and said other routes, including the A5, had extra traffic. Police said no-one was injured in the crash.
More on this and other news from Bedfordshire

The report into claims made in a BBC NI Spotlight programme has been complete for more than seven months.
Publication has been delayed by a legal challenge from Iris Robinson's solicitor.
A reference to the legal challenge is contained in an annual report from the Assembly's standards watchdog.
The Spotlight programme, broadcast in January 2010, detailed how Mrs Robinson had obtained thousands of pounds from property developers to help her teenage lover to set up a business.
Standards Commissioner Douglas Bain investigated the allegations, but his report has not yet been published.
"My investigation into the referral relating to the allegations made in the BBC Spotlight programme broadcast in January 2010 was completed in November 2013," he said.
"However, submission of my report to the committee has been delayed by a legal challenge to its contents by a person referred to in the report."
Iris Robinson's solicitor, John McBurney, told the BBC he had concerns about the impact upon his client of the production of a range of documentation included with the draft report.
Those concerns relate to the relevancy of the material to the inquiry, Iris Robinson's privacy and the impact publication might have on her health and recovery.
Motorists faced a sticky situation when a lorry shed its load of jam on the M1.
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A legal challenge has delayed the publication of an official report into allegations about the conduct of First Minister Peter Robinson and his wife.