Two in-game sources use the word Kalpa: http://uesp.net/wiki/Lore:The_Song_of_Pelinal,_v_7, and Paarthunax's dialogue. UESP doesn't actually cite the latter, but I'm willing to take their word for it; if you wanted to verify, you could probably find a video of the relevant scene somewhere. The Song of Pelinal quote is "he listed his bloodline in the Ayleidoon and spoke of his father, a god of the [previous kalpa's] World-River", referring to Umaril's speech to Pelinal as he died.
Neither of these actually explain what a kalpa is. I consider the Paarthunax example as a very obvious nod that we are to consider out-of-game sources here; if Paarthunax, being a "in-game lore" Dragon, mentions a concept from "obscure text lore" Nordic and Dragon ideas, then I would say that the in-game interpretation is the exact same as the out-of-game interpretation, as elucidated in http://www.imperial-library.info/content/world-eating-101 and the http://www.imperial-library.info/content/seven-fights-aldudagga. However, if you rejected this, then you would consider the word literally, IE, in http://en.wikipedia.org/wiki/Kalpa_%28aeon%29, meaning a very long period of time.
In my opinion, there isn't any evidence that kalpas, once you've defined them in game, actually happen; they're a feature of the Nordic (and according to Song of Pelinal, Ayleidoon) worldview rather than a concrete feature of the universe. Others feel differently, but I think there is not a load of difference between how the world actually works and how a group of people understand its working. But maybe the word of Paarthunax, being a small aspect of the very force of Time itself, is enough evidence to say that kalpas are definitely "real", whether as phenomenon or noumenon.
But I'm interested why you use the term "amaranthine continuum". Are you merely meaning amaranthine as in "everlasting", or is there a connection between the kalpa and the Amaranth?
Edit: the same concept as a "kalpic cycle" appears in http://www.imperial-library.info/content/monomyth-yokudan-satakal-worldskin under a different wording: the universe continually swallowing itself.