And I'm going to disagree back... I was going to try and explain, but wiki actually sums it up pretty well...
Geography (from Greek γεωγραφία, geographia, literally "earth description"[1]) is a field of science devoted to the study of the lands, the features, the inhabitants, and the phenomena of Earth.[2] ...Geography is an all-encompassing discipline that seeks an understanding of the Earth and its human and natural complexities—not merely where objects are, but how they have changed and come to be.
Geography is often defined in terms of the two branches of human geography and physical geography.[4][5] Human geography deals with the study of people and their communities, cultures, economies and interactions with the environment by studying their relations with and across space and place.[6] Physical geography deals with the study of processes and patterns in the natural environment like the atmosphere, hydrosphere, biosphere, and geosphere.
What you understand of geography is human geography, which
is more of a social science. Physical geography is very much a science in the same sense as geology, and overlapping in many aspects (though not interchangable IMO
@TenEightyOne)
While this statement isn't wrong, there is no way that anyone is an expert in all of it. In my old job, there were people who knew all there was to know about fluvial geology, but wouldn't be able to teach a basic volcanolgy course.
As another example - I could write: Biology is a rigorous discipline which requires a genuine understanding of chemistry, genetics, evolution, bacteriology, immune function, anatomy and many more. I know a decent amount about a few of those things, but by no means all of them.
Sorry, but that is an incredibly elitist view of your own field. You could swap 'geographer' and 'geologist' with any two other disciplines and still be a true statement.
Above, you say that geologists require knowledge of biology - I would bet my PhD on it that you couldn't do my job, and I am just as certain that I couldn't do yours, despite knowing a little bit of chemistry and having worked with geologists in my last job.