pipe-into gravel. Using steam points, spaced two to four feet apart, the miners thawed eight to ten feet per day, whereas wood fires could only thaw two or three feet per day.
For a time, dredging companies drove hundreds of points into the frozen ground in front of the dredges . However, this system left pillars of frozen ground for the dredge to dig through. Later, the miners realized that jets of cold water thawed more effectively than steam, and the steam points became obsolete.
