> land is not a finite resource
Land is relatively finite, but that's not what you said. You said arable land, and you did that intentionally because you know that arable land is what is relevant for wealth. Arable land is not at all finite, as I explained. You are right that I did not offer citation, but I also did not think I needed to. Obviously natural factors change the amount of arable land all the time. Some sources of this are: deforestation, pest population changes, crop disease/fungus or competitive plant life, water sources changing course or becoming salinated or drying up, desertification, terracing, urban sprawl. Then technological advances in agriculture also changes the amount of arable land. Some sources of this: irrigation, aquaculture, indoor farming, genetic modification of crops, fertilizers, pesticides, herbicides, etc.
> which is why it is effectively fixed for christs sake.
It has no relevance to the discussion of wealth stagnation or growth, and I am pretty sure you still don't understand that... or else you would have never brought it up.