Pentti Eskola was a Finnish geologist known for his significant contributions to the field of petrology, which is the study of rocks and their origins. He was born on March 15, 1883, and became a prominent figure in geology during the 20th century. Eskola is particularly recognized for developing the Eskola's metamorphic facies, a classification system that helps scientists understand the conditions under which different types of metamorphic rocks form. Throughout his career, Eskola conducted extensive research on the geology of Finland and other regions. His work laid the foundation for modern geological studies and influenced many geologists worldwide. Eskola passed away on December 27, 1964, leaving a lasting legacy in the scientific community.