It is very important to understand what geological description used in oil filed business. Hence, I collect the geological description from the book in order to be your reference and you will be able to understand meaning of each photo describing type of rock.
= Limestone (Ls)
= Dolomite&Chalk (Dol & Chk)
= Chert (Cht)
Limestones, Dolomite and Chalk are formed from large deposit of calcium carbonate (calcite) and calcium magnesium (dolomite).
= Gypsum & Anhydrite (Gyp & Anhy)
= Salt (Sa)
Gypsum, Anhydrite and Salt are composed of minerals precipitated from solution during evaporation of water.
= Basement (Bm)
= Volcanics (Volc)
Basement and Volcanics are formed from the cooling of molten magma.