Philo Judaeus De Aeternitate Mundi 118

[118] and he proceeds to establish the first point thus: if the earth had never had any beginning of its creation, then there would have been no portion of it rising above the rest so as to be conspicuous, but all the mountains would have been level, and all the pieces of rising ground would have been even with the plain. For as there are such vast showers falling from heaven throughout all ages, it would be natural that of any places which were originally raised on high some would be broken down and washed away by torrents, and others would subside of their own accord and so become lowered, and that every place everywhere would be smoothed;