Petrography rock was affixed to a microscope slide and then ground so thin that light could be transmitted through mineral grains that otherwise appeared opaque. The position of adjoining grains was not disturbed, thus permitting analysis of rock texture. Thin section petrography became the standard method of rock study. Since textural details contribute greatly to knowledge of the sequence of crystallization of the various mineral constituents in a rock, petrography progressed into petrogenesis and ultimately into petrology. It was in Europe, principally in Germany, that petrography advanced in the last half of the nineteenth century. The macroscopic characters of rocks, those
What Is This? project while the former was seen as side endeavor. What Is This released their debut EP "Squeezed" in 1984. Around this time, Hillel Slovak had become uncertain of his role in the band and decided to rejoin the Red Hot Chili Peppers. He left What Is This in 1985, and later that year the band would release its only full-length studio album "What Is This?" and its final EP "3 Out of 5 Live". After this, the band broke up. Alain Johannes later met Natasha Shneider and the duo formed Walk The Moon, whose sole studio album featured Jack Irons