"Eratosthenes of Cyrene, who lived basically in the third century B.C., was one of those first mathematicians whose knowledge and abilities at these early stages of human civilization was remarkable. Besides his method for seeking prime numbers, he particularly also contributed to the measurement of the Earth by, for example, determining its circumference. In this respect, he might have been the geomathematician, or at least one of the. Many more followed him, where definitely Carl Friedrich Gauss must be mentioned here, who can be seen as the greatest genius in mathematical history. His works and their in uence are widespread in mathematics and they are also of essential importance in various applications, in particular and (in the author's possibly biased point of view) first of all in Earth sciences, especially geomagnetics and potential theory. The awareness, which reaches back to the classical antiquity, that mathematics is the foremostly required skill and toolbox for understanding the objects and processes that surround us has been preserved up to the presence. It has nicely and more generally been put in a nutshell by the quotation above, which is from Kant (1786), for the English translation, see Kant (1883). Over the centuries, Earth sciences and mathematics have both advanced. While the achievements at the time of Eratosthenes and his fellows are nowadays parts of the curricula at schools, many modern challenges in geosciences are equally challenges to 21st century mathematics.Eratosthenes of Cyrene, who lived basically in the third century B.C., was one of those first mathematicians whose knowledge and abilities at these early stages of human civilization was remarkable. Besides his method for seeking prime numbers, he particularly also contributed to the measurement of the Earth by, for example, determining its circumference. In this respect, he might have been the first geomathematician, or at least one of the first. Many more followed him, where definitely Carl Friedrich Gauss must be mentioned here, who can be seen as the greatest genius in mathematical history. His works and their in uence are widespread in mathematics and they are also of essential importance in various applications, in particular and (in the author's possibly biased point of view) first of all in Earth sciences, especially geomagnetics and potential theory. The awareness, which reaches back to the classical antiquity, that mathematics is the foremostly required skill and toolbox for understanding the objects and processes that surround us has been preserved up to the presence. It has nicely and more generally been put in a nutshell by the quotation above, which is from Kant (1786), for the English translation, see Kant (1883). Over the centuries, Earth sciences and mathematics have both advanced. While the achievements at the time of Eratosthenes and his fellows are nowadays parts of the curricula at schools, many modern challenges in geosciences are equally challenges to 21st century mathematics"--