It was caused by the River Nith eroding an embankment under the railway during Storm Ciara, with 1,700 tons dislodged over a 50m section of track.
Following last weekend's Storm Ciara, the Met Office has warned that the next storm could bring another weekend of heavy wind and rain.
'Homes and businesses are likely to be flooded.
Storm Dennis: Highways teams on 24-hour alert
A further yellow-level rain and wind warning will follow tomorrow for south to south easterly winds of up to 60mph on coasts and high ground across southern Scotland, the Central Belt and Argyll. It has been issuing flood alerts throughout the week for parts of waterside communities including Lymington, Milford, Christchurch and Beaulieu.
It said it was making "all necessary preparations" for the forecast conditions.
The LNER train company has already cancelled dozens of services between London and the north-east of England.More news: Google gets in on the emoji mashup madness by launching 'Emoji Kitchen'
Other companies say services could be affected by speed restrictions as well as fallen trees and debris on the line.
It comes on a particularly busy weekend with many families having booked to travel over the half-term school holiday.
THE Highlands are bracing for further extreme weather this weekend - with the arrival of Storm Dennis amid warnings it could become one of the deepest Atlantic lows of modern times.More news: Former FBI deputy director Andrew McCabe won't be charged, Justice Department says
Meteorologist Matthew Box said: "The winds will be a touch down on what we saw with Ciara but the focus is on a bit more rain".
Forestry England hopes the routes will be reopened within days, but is also waiting to see how Storm Dennis affects the trails this weekend.
The Environment Agency is operating flood defences and flood storage reservoirs, and is ready to issue flood warnings and advice to those at risk ahead of the incoming weather.More news: Ericsson pulls out of MWC 2020 as Coronavirus concerns intensify
These include the Foss Barrier in York, the Thames Barrier in London and another in Bewdley, Worcestershire, on the River Severn.