Cob, daub, adobe, etc. What are all the natural "concretes" and what are they sourced from?

I often look longingly at people's cob creations and how they source the sand and clay from their own properties or near by. I have gravely loam soils. No clay. No sand. No easy, affordable way to make gorgeous, natural "concrete" creations. Or is there? Can loam soils be turned into building materials? This is a really new subject for me, so I'm probably really confused about everything. So far, these are the earthen building materials that I've found and a little info on them. Is there more that I'm missing?

Cob: Cob is a mixture of approximately 1 part clay, 4 ­parts sand and 1 part straw. (http://www.motherearthnews.com/green-homes/natural-building/cob-building-basics-zm0z13onzrob)

Daub:  Daub is primarily composed of earthen materials such as silt, sand, clay, and dirt. Earth can be a good building material due to its plasticity and compactability. However, earth does also have cohesive qualities which can be troublesome in humid regions and regions with great seasonal variations. Earth with large amounts of clay has higher cohesive qualities. To reduce cohesion, straw and sand can be added. (http://www.appropedia.org/Wattle_and_daub)

Adobe: Adobe bricks (mud bricks) are made of earth with a fairly high clay content and straw. If produced manually the earth mix is cast in open moulds onto the ground and then left to dry out. Adobe bricks are only sun-dried, not kiln-fired. When used for construction they are laid up into a wall using an earth mortar. Before drying out, the finished walls are smoothed down. Often a clay render is applied as a surface coating. (http://www.solidearth.co.nz/adobe-brick-technique.php)

Nicole,    I once too thought there was absolutely no clay to be found where I was living until one day I stumbled upon some soil that was 'different' to me. The shake and worm test lead to a brick test which confirmed I had finally found clay soil amongst all the sand, silt and rock that was everywhere else. Perhaps it just a matter of looking deeper? - pun intended (clay can often be below a few feet or the surface)

Definition of loam: https://en.wikipedia.org/wiki/Loam

So technically, if you have the correct type of loam, you no longer need to long for making your own creations out of a "natural concrete", you may already have clay and not know it - Perhaps even what is known  as "ready mix".

As far as not having much info on building with this material, I would have to disagree....there is tonnes of info just on permies alone.
There is also Rammed earth, Earth bag, Earthship, Plasters, clay paints etc.....

Hope this helps

yes i agree - you may not have dug deep enough to find clay.

the subsoil under the topsoil is where you find soils more suitable for natural building.

also if you know of any rivers nearby you could check along the river banks. clay will move along rivers and be found in pockets after the rivers deposit it there.
walking along the river you may be able to spot the clay pockets along the river bank.