In the winter of 1850-51 it was reported that Cider Cone, located ten miles east of Lassen Peak had erupted.
Enter, San Francisco physician Harvey W. Harkness, who had a keen interest in scientific matters. In the summer of 1874, he visited Plumas County. While there he heard the story of a recent volcanic eruption located in far northern portion of the county known as Cinder Cone. Since he was already in the territory, he decided to examine Cinder Cone. In the fall, Harkness addressed the California Academy of Sciences and told of his observations. He informed the Academy that the eruption was indeed of recent origin. After his presentation, he came on contact with with four men who had seen the eruption from afar. One of these men was Oliver Wozencraft, who lived near Red Bluff during the winter of 1850-51. He informed Harkness that he saw a great fire east of Lassen that continued for many nights but never changed its position.
After Harkness’ findings were published, it served as a reminder to many that a volcanic eruption could be impending. It was not for decades that Harkness’ theory was challenged. The whole issue was resolved in the 1990s by the United States Geological Survey, which determined that Cinder Cone’s last eruption occurred sometime around 1666 and not 1850.