The dates and time are my best guesses. Somewhere around 1980, summer time, in early evening my wife, brother, his wife and I were driving down highway 1 in Pacifica in a southbound direction. As highway 1 is on the ocean we looked out to sea and saw a bright blue light in the form a straight line to the horizon both north and south moving from the west to east. We were in a car so we hurried to our home which was on a hill about a half mile away but was in the path of the light which seemed to move very slowly (maybe about 10 mph). Upon reaching my home before the light got there my brother and I got out of the car and waited a minute or so until it reached us. The lighted line was solid and appeared to be about one foot in width and about the same in height or thickness. It was right on the surface of the ground and traveled along the contours of the earth like it was a bar code reader. It went right over and through us and continued eastward until it was out of sight. We called the police and reported it and they said that others had called also. There were no visible aircraft of any kind that we could see. As the line was first noticed over the ocean we could see that it was a straight line as far as we could see both to the North and to the South over the water. We felt nothing when it went over us. The color was only blue like the color blue in the writing above this box on your website. It may have been a little lighter but was very obvious. Also, I spoke to someone at Mufon about this years ago but wanted to put it in writing. I read and was told that this event has been reported about every 50 years for at least a couple hundred years.