A study of the F-layer of the ionosphere made with an HF backscatter radar using a narrow-beam antenna has revealed a large number of irregularities in the size range from 50 to 500 km in north-south extent. It was possible to divide these irregularities into 5 types which were named spot, line, split, step, and range variable. On the basis of 60 one-hour records, the probability of the occurrence of each type was estimated (spot: 60%; split: 90%; others: less than 20% of the time). North-south motion of the irregularities was observed, but it occurs less than 10% of the time and always with movement from north to south. When observed, the average velocity of movement is of the order to 1000 km/hr. On occasion, growth and fade of the irregularities was noticed, with the time from start of growth of time of fade-out being of the order of 10 to 15 minutes.