30. How do we distinguish the two groups into which igneous rocks are
subdivided? What is meant by the terms _amygdaloidal_ and
_porphyritic_?
31. Name some rocks that belong to the acidic group. What is
_quartz-porphyry_?
32. Give examples of augitic igneous rocks. Name a hornblendic igneous
rock.
33. What are fragmental igneous rocks? What is the difference between
_trappean breccia_ and _trappean conglomerate_?
34. What is meant by the terms _stratum_, _strata_, and _stratified_?
What is the difference between _lamination_ and _bedding_? What is a
section?