The early observations of Dr. James Hutton - A little bit of biography -How he became interested in geology -Geologic foundations -Early observations -Siccar Point -Graphic Granite -Glen Tilt

Some biographic details Born – June 3, 1726 Died - March 26, 1797 Born, raised, and educated in Edinburgh, Scotland Started at University of Edinburgh in 1740, became interested in chemistry Brief period as a lawyer, then moved to medical school Moved to the continent to finish school Picture from: MAGELLAN Geographix

Doctor  Farmer Chemical background – discovered new way to refine “sal ammoniac” – salt of ammonia Business started by James Davie, with Hutton as a partner –Guaranteed financial support Picture from:

Farming and Soil Specialized in mineralogy – rock chemistry Applied to farming, to understand chemistry of soils and affects on crops Noticed benefits of “marl” – clays, carbonates, and organics – quicklime –Enclosed fields to prevent erosion

Erosion and Deposition Hutton’s early essay “On the Natural History of the Earth” stressed –Rocks can be made of old eroded materials –Debated over the method Read works of Nicolaus Steno – laws/principles of deposition –Superposition –Lateral Continuity –Original Horizontality – “It is certain that many of the strata hae been moved angularly, because that, in their original position they must have been all nearly horizontal.” Playfair – p 42 Also – Intrusive Relationships

Unconformities Contact between two rocks of different ages – a buried erosional surface Represents “gap in time” Picture from Cornell University

1 – Siccar Point Picture from: Picture from: University of Pittsburgh Picture from: The University of Edinburgh Unconformity Sandstone Graywacke Unconformity Sandstone Graywacke

“Plutonian” Believed in consolidation of rocks by “subterranean heat”- but couldn’t explain it Disagreed with Werner and “Neptunists” –Insoluble sediment precipitated first - Primitive –Crystals intermingled

Refuting the Neptunists Deny the power of water as solvent to many rock constituents “To affirm that water was ever capable of dissolving these substances, is to ascribe to it powers which it confessedly has not at present; and to introduce a hypothesis which is absurd and impossible” – Playfair, p. 18

A harsher refutation “The Neptunists must either assign a sufficient reason for this great and universal change, or must expect to see their system treated as an inartificial accumulation of hypotheses which assigns opposite virtues to the same subject, and is alike at variance with nature and with itself; in a word, a system that might pass for the invention of an age, when as yet found philosophy had not alighted on the earth, nor taught man that he is but the minister and interpreter of nature, and can neither extend his power nor his knowledge a hair’s-breadth beyond his experience and observation of the present order of things.” Playfair, p. 18,19

2 – Graphic Granite Feldspar and Quartz crystals interwoven – must have crystallized at same time – not “settled out of solution” “…the quartz is impressed by the rhomboidal crystals of the feltspar…” Playfair, p. 86 Picture from: Univ. of Western Ontario

2 – Graphic Granite “…melted whin, by regulated or flow cooling, is prevented from assuming the appearance of glass, and becomes a stony substance, hardly to be distinguished from whinstone or lava” – Playfair, p. 80 Postulated rocks from molten origins, more “subterranean heat”

3 - Glen Tilt Map from: USGS Museum collection Watercolor map by Hutton Sandstone/ Graywacke Intruded Sediments

3 - Glen Tilt Granitic dikes through sedimentary strata “in every conceivable manner” Sedimentary strata required to be younger Granite required to be fluid “…melted by the force of subterraneous heat, and injected among the rents and fissures of the rocks already formed. In this manner were produced the veins and dikes of whinstone…” Playfair, p. 81 Nonconformity – sedimentary touching igneous

John Playfair Became acquainted with Hutton later in life Published “Illustrations on the Huttonian Theory of the Earth” – a restatement of Hutton’s work (a work with no pictures) “Illustrations” was a rewording in support of Hutton’s “Theory” – an easier read

Books to read Repcheck – The Man Who Found Time, 2003 Baxter – Revolutions in the Earth, 2003 Bailey – The Found of Modern Geology, 1967

References Playfair, John, Illustrations of the Huttonian Theory of the Earth, Constable and Company, London, 1956 Repcheck, Jack, The Man Who Found Time, Perseus Publishing, 2003 Bailey, Edward, James Hutton – The Founder of Modern Geology, Elsevier Publishing Co. Ltd., 1967 Baxter, Stephen, Revolutions in the Earth: James Hutton and the True Age of the World, Weidenfeld & Nelson, 2003