A link is worth more than 1000 words: https://productforums.google.com/forum/#!topic/calendar/O2fpZq36otA
This Chrome Extension fixes this annoying behavior and disables the scroll on the calendar grid in Google Calendar. You won't be able to navigate to next/previous month using the scroll. You will have to use the arrows < > buttons, as normal people expect it to be.
You can find the latest version on the Chrome WebStore:
https://chrome.google.com/webstore/detail/google-calendar-scroll-di/nghndfiaocgpmcbeafglhknklfgddebe
App icon is by Maxim Basinski