Foraminifera are used in geology and by the oil industry as invaluable aids in the determination of the age as well as the depositional environment of strata. From 1940 to 1943, Parker worked as a secretary at Foxcroft, an exclusive girl s school in Middleburg, Virginia. In 1943, she received several offers to work as a scientist in the petroleum industry and accepted a position at Shell Oil Company. Parker recalls that her interest in ecology began in Houston, and that the Shell Oil Company group with which she worked broadened her interests from foraminifera taxonomy to the application of the tools of micropaleontology to studies of the environment. There is a natural connection between foraminifera research and the petroleum industry.
Petroleum is generated by heating organic matter deposited within marine sediments.
Some such sediments are particularly rich in organic matter and make good source rocks. This information helps in exploration for undiscovered petroleum deposits. Consequently petroleum companies have long been interested in and have supported work in this field, especially during periods when petroleum exploration was very active. Parker was appointed Senior Paleontologist at Shell Oil Company in 1943, but left the company after three years when she became ill with tuberculosis. He had a small research grant from WHOI, and Parker joined him to undertake work on foraminifera taxonomy, working largely on foraminifera of the Atlantic.