This is the origin of the mineral called travertine or calcareous tufa, which is so commonly met with on the margins of springs, rivers, and waterfalls.
"Geology"
James Geikie
But in the books of the best printers of our own day, as well as in those of the best of the fifteenth century, from 65 per cent to 72 per cent of the height of the page is devoted to the text, from 28 per cent to 35 per cent being reserved for the upper and lower margins, of which at least two-thirds is for the lower and not more than one-third for the upper.
"Fine Books"
Alfred W. Pollard
It is easiest to see in the case of the relation between the inner and outer margins.
"Fine Books"
Alfred W. Pollard