In this study altimeter gravity and ship track bathymetry data from National Geophysical Data Center (NGDC) is explored to investigate the relation between roughness of gravity and bathymetry data to the age of oceanic crust over 90 degrees E Ridge. The gravity and bathymetry profiles are selected over the ridge at places of known ages from Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP). The gravity and bathymetry data are gridded at sampling interval of 1' 12" and profiles are extracted on the DSDP and ODP sites. The roughness of gravity and bathymetry data is computed as the square root of the average squared deviation about a linear trend. The roughness varies as a power -1.31 and -1.59 of age for bathymetry and gravity data. The mean fractal dimension is found to be 1.54 and 1.46 for bathymetry and gravity data. The roughness of bathymetry and gravity data varies with age with different power law. It is also interesting to note that the roughness of bathymetry decreased with age, which indicates modification of bathymetry data in the older (northern) portion of the ridge with continuous depositions of Bengal fan sediments.