Bram Stoker's Dracula

In 1462, Vlad Dracula, a member of the Order of the Dragon, returns from a victory against the Turks to find his wife, Elisabeta, has committed suicide after receiving a false report of his death. Enraged that his wife is now damned for committing suicide, Dracula desecrates his chapel and renounces God, declaring that he will rise from the grave to avenge Elisabeta with all the powers of darkness. In a fit of rage, he stabs the chapel's stone cross with his sword and drinks the blood which pours out of it.
In 1897, newly qualified solicitor Jonathan Harker takes the Transylvanian Count Dracula as a client from his colleague R. M. Renfield, who has gone insane. Jonathan travels to Transylvania to arrange Dracula's real estate acquisition in London, including Carfax Abbey. Jonathan meets Dracula, who discovers a picture of Harker's fiancÃ©e, Mina and believes that she is the reincarnation of Elisabeta. Dracula leaves Jonathan to be attacked and fed upon by his brides and sails to England with boxes of his native soil, taking up residence at Carfax Abbey. His arrival is foretold by the ravings of Renfield, now an inmate in Dr Jack Seward's neighboring insane asylum.
In London, Dracula emerges as a wolf-like creature amid a fierce thunderstorm and hypnotically seduces, then rapes and bites Lucy Westenra, with whom Mina is staying while Jonathan is in Transylvania. Lucy's deteriorating health and behavioral changes prompts Lucy's former suitors Quincey Morris and Dr Seward, along with her fiancÃ©, Arthur Holmwood, to summon Dr Abraham Van Helsing, who recognizes Lucy as the victim of a vampire. Dracula, appearing young and handsome during daylight, meets and charms Mina. When Mina receives word from Jonathan, who has escaped the castle and recovered at a convent, she travels to Romania to marry him. In his fury, Dracula transforms Lucy into a vampire. Van Helsing, Holmwood, Seward and Morris kill Lucy out of mercy the following night.
After Jonathan and Mina return to London, Jonathan and Van Helsing lead the others to Carfax Abbey, where they destroy the Count's boxes of soil. Dracula enters the asylum, where he kills Renfield for warning Mina of his presence. He visits Mina, who is staying in Seward's quarters while the others hunt Dracula, and confesses that he murdered Lucy and has been terrorizing Mina's friends. A confused and angry Mina admits that she still loves him and remembers her previous life as Elisabeta. At her insistence, Dracula begins transforming her into a vampire. The hunters burst into the bedroom, and Dracula claims Mina as his bride before escaping. As Mina changes, Van Helsing hypnotizes her and learns via her connection with Dracula that he is sailing home in his last remaining box. The hunters depart for Varna to intercept him, but Dracula reads Mina's mind and evades them. The hunters split up; Van Helsing and Mina travel to the Borgo Pass and the castle, while the others try to stop the gypsies transporting the Count.
At night, Van Helsing and Mina are approached by Dracula's brides. They frighten Mina at first, but she gives in to their chanting and attempts to seduce Van Helsing. Before Mina can feed on his blood, Van Helsing places a communion wafer upon her forehead, leaving a mark. He surrounds them with a ring of fire to protect them from the brides, then infiltrates the castle and decapitates them the following morning. As sunset approaches, Dracula's carriage arrives at the castle, pursued by the hunters. A fight between the hunters and gypsies ensues. Morris is stabbed in the back during the fight and at sunset Dracula bursts from his coffin. Harker slits his throat while a wounded Morris stabs him in the heart with a Bowie knife. As Dracula staggers, Mina rushes to his defense. Holmwood tries to attack but Van Helsing and Harker allow her to retreat with the Count. Morris dies, surrounded by his friends.
In the chapel where he renounced God, Dracula lies dying in an ancient demonic form. They share a kiss as the candles adorning the chapel light up and the cross repairs itself. Dracula turns back to his younger self and asks Mina to give him peace. Mina shoves the knife through his heart and as he finally dies, the mark on her forehead disappears as Dracula's curse is lifted. Tearfully, she decapitates him and gazes up at the fresco of Vlad and Elisabeta ascending to Heaven together, reunited at long last.

Question: What do Jonathan and Van Helsing lead the others to destroy at Carfax Abbey ?
Answer: The Count's boxes of soil.