LADD, HARRY STEPHEN

(b. St. Louis, Missouri, 1 January 1899; d. Bethesda, Maryland, 30 November 1982),

paleoecology, coral reefs, Pacific Islands geology and paleontology.

An expert on the geology of the islands of the Pacific, Harry Ladd spent many years studying that ocean’s atolls and coral reefs. The Treatise on Marine Ecology and Paleoecology (1957), the second volume of which he edited, created the foundation for decades of paleoecology work. He also promoted a project that produced Bikini and nearby Atolls, which became the authoritative work on the geology, biology, and paleontology for much of the Pacific. His drilling at Enewetak Atoll essential confirmed Charles Darwin’s postulate that the atoll shape was the result of subsidence.

Early Life and Career . Harry Ladd was interested in nature as a youth, and the summers that his family spent at Bar Harbor, Maine, whetted his interest in marine invertebrates. This led in turn to an interest in fossils, encouraged during his years at Washington University in St. Louis. Ladd received his master’s degree in 1924 and doctorate from the University of Iowa in 1925, his thesis work based on study of an Ordovician rock formation in Iowa and its contained fossils, published as “Stratigraphy and Paleontology of the Maquoketa Shale of Iowa” (1929). During this interval he was also an assistant geologist on the Iowa Geological Survey. Intrigued by the Devonian fossil coral reefs of Iowa, he obtained a fellowship from Yale University and the Bernice P. Bishop Museum in Honolulu to examine Cenozoic and Recent reefs. He traveled to Fiji and marked this trip as the year he had no birthday, as a result of the ship crossing the International Date Line just at the close of 31 December. Following his first efforts in the South Seas, he taught from 1926 to 1929 at the University of Virginia. Disliking teaching, he then worked for two years in Venezuela as a paleontologist for the Gulf Oil Company of Venezuela. Living on money he had saved, Ladd spent a year studying his collections of fossils from the Fiji Islands at the National Museum of Natural History in Washington, D.C. During a second year, he worked as an assistant for the U.S. Geological Survey (USGS) and continued his paleontological investigations in the evenings.

In the Pacific . During his first ten years of activity in the Pacific, nearly three were spent in fieldwork. In 1934 Ladd and J. Edward Hoffmeister of the University of Rochester returned to the Fiji Islands and laid the basis for all future detailed mapping of the island group. More importantly, they studied the reefs and concluded that subsidence was not necessary for coral growth and that water level fluctuation due to glaciation was not a significant factor in reef formation. Ladd persuaded his fiancée, Jane Mahler, to travel to Fiji, where they were married. He was presented with a sperm whale tooth that thereafter graced their double bed. They had two sons and, at the time of his death, four grandchildren.

U.S. Geological Survey . Upon the couple’s return to the United States in 1936, Ladd joined the National Park Service, first as a district geologist for Atlanta and Richmond and then rising to regional geologist in 1938. The work included examining water supplies in various regions, drilling water wells, and locating sites of construction material, these investigations engendered in part by the Tennessee Valley Authority. During 1940 he transferred to the USGS, retiring from that organization in 1969.

Ladd’s first USGS assignment was to study the Late Cenozoic and Recent marine invertebrates of the Texas Gulf Coast. This study was probably arranged by T. Way-land Vaughan, a pioneer in the study of corals, who had left the USGS to head the Scripps Institution of Oceanography in San Diego, California, and later returned to the National Museum, where he advised Ladd in his study of the Fiji fossils. In 1940 Vaughan organized the Subcommittee on the Ecology of Marine Organisms under the Committee on Geologic Research of the National Research Council. Impressed by Ladd’s organizational skills and enthusiasm, Vaughan arranged for his appointment as chairman of the subcommittee.

The subcommittee was moribund during the crisis of World War II, which also ended Ladd’s investigations of Gulf Coast marine organisms. Instead, in 1941 and 1942 he investigated manganese deposits in the Appalachian Mountains. During 1942 he was transferred to Rolla, Missouri, as a regional geologist to coordinate investigations for strategic minerals in midcontinent. After the war Ladd returned to Washington, D.C., and served as an assistant chief geologist of the USGS from 1946 to 1949.

Despite his official administrative activities, Ladd made the time to reconstitute his earlier panel into a Committee on Marine Ecology and Paleoecology. In scarcely more than a decade, the Treatise on Marine Ecology and Paleoecology (1957) was published. It consisted of two volumes, the second of which, titled Paleoecology, was edited by Ladd. At 2,372 pages, the two volumes were the largest single publication of the Geological Society of America. It laid the basis for half a century of studies in paleoecology.

Studying Pacific Atolls . As part of his official duties, Harry Ladd recommended and outlined a project for the USGS to map a number of island groups in the Pacific. The project began in 1946 and lasted for fifteen years, producing invaluable geologic data. More or less simultaneously, he was engaged in fieldwork, surveying Bikini Atoll in advance of atomic bomb testing. Ladd returned in 1947, following the tests. This project led to the publication of USGS Professional Paper 260, Bikini and nearby Atolls. Its thirty-five chapters of more than one thousand pages and more than three hundred plates make it by far the largest USGS professional paper. It is the standard reference for many aspects of the geology, biology, and paleontology of a vast portion of the Pacific region.

In connection with investigations at Enewetak Atoll, Ladd made his third major contribution to geology. To better understand the formation of atolls, considerable core drilling was undertaken, most of it under the direct supervision of Ladd, who logged wells and collected cuttings with the rest of the crew. Drilling was done on a barge towed from Hawaii carrying a Failing 1500 Hole-master rig. The actual drilling at Bikini and Enewetak Atolls was done by Virgil Mickel, an Oklahoma driller Ladd had employed during his time with the National Park Service.

At Enewetak, Mickel drilled through more than 4,000 feet of reef rock before reaching the basalt from a sunken volcano. Ladd hung up a sign “Darwin was Right.” Charles Darwin had postulated that the atoll shape was the result of subsidence. Careful study of the cores indicated fluctuations in subsidence and changes in sea level, however, so those who argued against Darwin’s hypothesis were correct in a few details.

Project Mohole . Because of this experience of drilling from a barge in a lagoon, Ladd was the logical person to try test drilling in open water for scientific purposes. This explains Ladd’s involvement in the proposed Project Mohole, an attempt to drill down to Earth’s mantle layer. The effort was never completed, but continuous drilling from 1958 to 1966 resulted in vastly expanded geologic knowledge of the world’s ocean basins.

Honors and Awards . After his official retirement in 1969, Harry Ladd continued his investigations at the National Museum for another full decade until his activities were curtailed by Parkinson’s disease. Ladd was president of the Paleontological Society in 1954, a vice president of the Geological Society of America in 1955, and a vice president of the American Association for the Advancement of Science in 1965. He received the Department of Interior’s Distinguished Service Award in 1965 and was awarded the Paleontological Society Medal in 1981.

BIBLIOGRAPHY

WORKS BY LADD

“Stratigraphy and Paleontology of the Maquoketa Shale of Iowa.” Annual Report of the State Geologist 34 (1929): 305–448. Editor. Treatise on Marine Ecology and Paleoecology. Vol. 2, Paleoecology. Geological Society of America, memoir 67. New York: Geological Society of America, 1957.

OTHER SOURCES

“Paleontologist Harry S. Ladd Dies.” Washington Post, 2 December 1982.

U.S. Geological Survey. Bikini and nearby Atolls, Marshall Islands. Professional Paper 260 (parts A-II). Washington, DC: Government Printing Office, 1954–1969.

Whitmore, F. C., and J. I. Tracey Jr. “Memorial to Harry Stephen Ladd, 1899–1982.” Geological Society of America Memorial 14 (1984): 1–7.

Yochelson, E. L. “Presentation of the Paleontological Society Medal to Harry Stephen Ladd.” Journal of Paleontology 56 (1982): 826–827.

Ellis Yochelson