Vittorio Tredici (1892-1967) was a highly experienced mineralogist who carried out research on behalf of mining companies specializing in the study of phosphates in Transjordan. From his certificate on Valtortian work, we take up the more specific passages regarding his competence:
What struck me most deeply, from a critical point of view, in the Work was the perfect knowledge that the writer had of Palestine and the Places where the Preaching of Our Lord Jesus Christ took place. Knowledge that in some passages goes beyond the normal geographical or panoramic knowledge, to become even topographical and even more geological and mineralogical. From this point of view, especially for the area beyond the Jordan (present day Jordan), there are no publications – as far as I know – so detailed as to make it possible even for a scientist, who has not been on site on purpose, to be able to imagine and describe entire paths with such perfection as to make those who have had this possibility perplexed.
I have traveled through Palestine and Jordan and other Middle Eastern countries on numerous trips. I paused, in particular, in Jordan for mining research and therefore I was able to see and follow with a careful eye what brief and not precise English publications (the only ones that I believe exist on the subject, for those areas) cannot even remotely offer.
Therefore I can declare, in clear conscience, that by reading the description made in the Work of one of the travels of Jesus beyond Jordan up to Gerasa, I recognised, in a perfect way, with the living memory that leapt to my mind from the reading, the path of Our Lord, and I recognised the description made with such precision that only those who could either see or have seen it had the chance to be able to portray it! But my surprise was accentuated when, continuing to read, I read a declaration of a mineralogical nature, where representing protruding dikes similar to granite she states that they are not granites but limestones! I declare that this distinction could only be appreciated – on site – by an expert! And continuing, I still read that on the summit, not far away, before resuming the slight descent to Gerasa, there is a small spring where Jesus stopped with the convoy to have a short breakfast. Now I think that this source, which exists, is of such a modest entity that it would have escaped anyone who had not been particularly attentive, even passing through it.
The writing that we have reported in part is from 1952.