Topographic Image of Stepped Crater (IMAGE) Virginia Tech Caption A topographic image shows the experimental fan emerging from the channel and depositing on the crater floor. The experimental mock crater in the image is 1.5 m across. The fan is about 40 cm across. The notches in the fan move down the fan like stair steps. Each distinct step represents an intersection of when the rising shoreline hit the depositing fan surface. Credit Erin Kraal Usage Restrictions Use with report of Kraal's research License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.