As promised, and with no offense intended, here is an example of an area from an existing 100k geology dataset of Clark County that is clearly inadequately detailed from my perspective as a surficial mapper:
I made the contacts red to be obvious. Most of the tonal variations that you see in the image represent distinct surficial piedmont units. Many that have been lumped together are quite large and also span a huge range of time as far as surficial deposits go. Also it is not clear why some large active washes were mapped individually and other, larger ones weren't. This approach to mapping is covered in the unit descriptions from this map for the most part, but for our purposes, additional mapping is certainly required.