Jordan179 has made a tentative reconstruction of Earth's past political geography, based on the Kadath murals, the Pnakotic Manuscripts, testimony of channeled time travelers, and other fragmentary evidence of the deep past surviving to the present. He has correlated geological evidence for the position of the continents (noting Lovecraft's use of continental drift, at the time a disputed and largely rejected fringe hypothesis that would become the dominant geological paradigm a generation later).
I find the positioning of R'lyeh somewhat odd, placing it what would become central and northeastern Asia, but the scope of the future continent is still unknown so any suggestion at this point is tentative. And it keeps in the commendable spirit of many chroniclers of Earth's hidden history, with two sources rarely agreeing. And then there is the issue of the Cthulhi/Xothians and water, which has been discussed extensively elsewhere. I think there is a methodological issue in presenting this as somewhat static, collapsing vast amounts of time (the map is labeled as varying through time, but considering the huge amounts of time involved ...). But then, the source material also stretches empires over tens of millions of years, or longer, so this isn't out of character with the evidence.
But overall, an interesting approach to a problem typically handled textually. It reminds me of the culture history maps from archaeology's early professional days, when large blobs and arrows would translate artifacts, postmolds, and art styles into nation-like units to build histories before history. V. Gordon Childe, one of the most influential of culture historians, was publishing his reconstructions of Eurasian prehistory precisely at the time Lovecraft was writing the stories that most directly under gird this map. I find it quite fitting.