Petrology and cycles and the use of thermodynamic data and experiments in order to better understand the origins of rocks. There are three branches of petrology, corresponding to the three types of rocks: igneous, metamorphic, and sedimentary, and another dealing with experimental techniques: Petrology Petrology (from the Greek πέτρος, "pétros", "rock" and λόγος, "lógos", "subject matter", see -logy) is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because they both contain heavy use of chemistry, chemical methods, and
What Love Is Made Of three minutes and fifty-five seconds (3:55), "What Love Is Made Of" is an uptempo dance and house track that has been described as "rave-y" and "trance-y". Its instrumentation contains the sounds of pianos and synthesizers. Jordan Sargent of "Spin" observed that it continued the musical style first introduced in Katy's 2012 extended play (EP), "Danger EP", which was "straight-forward house". Idolator's Sam Lansky compared her performance in the song to recording artist Siobhán Donaghy. Critical response to "What Love Is Made Of" was generally positive: most critics noted Katy's vocal performance and commended its sound. Siân Rowe from "NME" was