The log struck Sloan from behind causing him to fall further down the gully, and he suffered multiple injuries, including crushing injuries.
The operation of a digger by another employee about 80 to 100m above the victim was found to have increased the risk of a log being dislodged and serious harm to a worker.
Sloan was flown to Waikato Hospital for life-saving surgery, which included removing part of his bowel and repairing his appendix.
His other multiple injuries included lacerations to his liver, a ruptured bladder, a shattered left hip, fractured femur and several fractures to his lower spine.
Sloan, who now walks with a limp, told the court that he would eventually need a total hip replacement and the accident had changed his life and life of his family "forever".
WorkSafe New Zealand's prosecutor Lucy Moffatt submitted that given the extent of the injuries suffered by the victim, a higher reparation award than usual should be awarded.
Cropp Logging's lawyer Bill Lawson said his client, which was insured, would pay whatever Judge Thomas Ingram felt was fair.
But in terms of overall culpability, the judge should distinguish this prosecution case from others where there was a complete lack of health and safety procedures in place.
"This was clearly a case of absence of vigilance by another employee in following the standard health and safety practices set out by the company," Lawson said.
Judge Ingram said while he agreed there were some distinguishing factors, the extent of the injuries suffered by Sloan put this case into an entirely different sentencing category.
"I have to say it is difficult for me to think of a more serious set of injuries other than someone who has been left totally incapacitated, " the judge said.
Judge Ingram said the impact on Sloan and his family was clearly "enormous", both financial and the psychological trauma.
This was such a serious breach of the Health and Safety at Work Act that he would have imposed a $375,000 fine if the defendant could have afforded to pay it, the judge said.
But Judge Ingram said in setting the fine he took to account that Cropp Logging was a small family-owned business which had an otherwise "long and very good safety record".
He fined Cropp Logging $100,000 and ordered the company to pay Sloan $80,000 reparation.
The company was also ordered to pay $10,000 costs to WorkSafe.