Karen Wynn Fonstad has published a very comprehensive collection (210 pages) of maps in The Atlas of Tolkien's Middle-earth, with (estimated) some two thousand references on different subjects like topography (maps - lots of them in different scale), travel routes, army movements (plus estimates on the sizes of these) in different battles, architecture, landforms, climate, vegetation, population and languages.
Just an example, a little spillover from my HD, from some notes on the occurrence of red rock in Middle-earth - this bit on the Misty Mountains and Moria. I don't know if such info is useful for your mapping, but here it is:
... Red stone was mentioned near both Rivendell and Moria. In the Trollshaws the East Road cut through 'moist walls of red stone on its last leg, descending to the Ford of Bruinen [...] In the western part of the Trollshaws Thorin and company crossed a 'rushing red' river, indicative that it was carrying sediment from the red soil [...] Near Moria the Fellowship scrambled through a barren country of 'red stones' [...] In the mountain range itself, only Caradhras was noted as the 'Redhorn' while the other rock was described as gray. It seems unlikely that Caradhras, the tallest of the Mountains of Moria, would have been composed of the same red rock found in the foothills - especially as the other peaks were obviously of different material. One of two things may have accounted for its color: Its bedrock was a third rock type not present in either the foothills or the surrounding mountains, or its bedrock was not red at all but merely reflected rays of the rising sun.
One additional factor may shred light on the subject - mineralization. The lodes of mithril, an ore found nowhere else, were 'north towards Caradhras, and down to darkness'. Veins of precious ores normally result from repeated igneous intrusions into faults. If intrusions had occurred, extrusions might have also been present; and the Redhorn might have been an isolated peak of igneous rock, such as andesite porphyry, which is dull pink or red.
