A Geological Ode To Charles Darwin

And so really, it's just a scandal that the biologists have absconded with Darwin's memories.....He's ours. He's a geologist, and we're filing a class action suit..

Geophysicist Ross Stein of the USGS makes a good case in a discussion which turns into a tribute on Science Friday that Charles Darwin had foundational influences not just in biology but in geology as well.

On February 20th 1835 Darwin was ashore in Valdivia on the Chilean coast when a great earthquake struck.

From The Voyage of the Beagle: [page] 369 Feb. 1835. GREAT EARTHQUAKE.

The day has been memorable in the annals of Valdivia, for the most severe earthquake experienced by the oldest inhabitant. I happened to be on shore, and was lying down in the wood to rest myself. It came on suddenly, and lasted two minutes;

On March 4th the H.M.S. Beagle sailed into Concepcion port and Darwin and his crew witnessed a town devastated. He along with Capt. Fitzroy wrote about the damages and human suffering in their diaries.

But soon the scientist in Darwin took over and he made several insightful geological observations and reflections on vertical movements of the crust during earthquakes and associated volcanic and magmatic activity and their link to the formation of mountains chains:

[page] 379 March 1835. VOLCANIC PHENOMENA.

It is almost certain, from the altered soundings, together with the circumstance of the bottom of the bay near Penco, consisting of hard stone, that there has been an uplifting to the amount of four fathoms, since the famous convulsion of 1751. With this additional instance fresh before us, we may assume as probable, according to the principles laid down by Mr. Lyell,* other small successive elevations, and may fearlessly maintain that the problem of the raised shells,† recorded by Ulloa, is explained.

And then he astutely links the earthquake clusters with the coincident volcanic activity into an explanation for the formation of mountain chains:

[page] 380 CONCEPCION. March, 1835.

The elevation of the land to the amount of some feet during these earthquakes, appears to be a paroxysmal movement, in a series of lesser and even insensible steps, by which the whole west coast of South America has been raised above the level of the sea. In the same manner, the most violent explosion from any volcano is merely one in a series of lesser eruptions: and we have seen that both these phenomena, which are in so many ways related, are parts of one common action, only modified by local circumstances. With respect to the cause of the paroxysmal convulsion in particular portions of the great area which is simultaneously affected, it can be shown to be extremely probable, that it is owing to the giving way of the superincumbent strata, (and this giving way probably is a consequence of the tension from the general elevation) and their interjection by fluid rock—one step in the formation of a mountain chain. On this view we are led to conclude, that the unstratified mass forming the axis of any mountain, has been pumped in when in a fluid state, by as many separate strokes as there were earthquakes.

He saw raised beaches and altered depth soundings...conclusion.? ..the crust moved vertically during earthquakes...this must have happened many times in the past as well...applying Charles Lyell's principle of uniformitarianism...

..so..along with injections of magma, such episodic movements of the crust will eventually form high mountain chains like the Andes... and as Ross Stein elaborates...since these processes occur only episodically, it must be taking millions of years for mountains to form...therefore the earth must be really really old.

aside from these fundamental insights he explains the origin of batholiths oriented along the axis of mountains:

On this view we are led to conclude, that the unstratified mass forming the axis of any mountain, has been pumped in when in a fluid state, by as many separate strokes as there were earthquakes.

 
Not bad coming from one of the foundational figures of..modern biology.

What really struck me was the striking contrast in his descriptions of the gradual process of mountain building as against the gradual process of organic evolution. For mountain building he envisioned violent episodic events..the convulsions and paroxysmal earth movements that raised the crust in leaps and bounds and those new elevations gradually accumulated to raise the crust to great heights. Earthquakes were disruptive events and in between .... nothing happened...it was long periods of boredom followed by short periods of terror. Mountains formed through gradual but discontinuous processes.
 
Contrast this with his mechanism of biological evolution which also consisted of gradual change but one of a different nature. It proceeded through tiny changes which accumulated continuously..generation after generation. The rate of change may not necessarily be the same but change was continuous. He positively rejected the idea of disruptive changes or discontinuities when it came to explaining the origin of organic form. Traits did not come into existence through sudden leaps. His mechanism of natural selection acting on slight variations among individuals in a population demanded that descendants would differ only by very tiny increments from their immediate ancestors. Organic evolution therefore had to be gradual and continuous.

Ross Stein is right. Darwin was more than a competent geologist and he thought very deeply about geology...he had to.. since the abrupt appearance of new species and groups in the fossil record was a headache for him. This he explained mostly on the geological grounds of the presence of massive discontinuities in the preservation of sediments and fossils.

But he also saw a much more fundamental difference between geological processes and organic evolution and the difference was one of uniqueness.

For him, geological processes were part of the grand recycling of the planet. Magma rose up and solidified as rock. That rock over eons got weathered and the resulting sediment got buried and remelted into magma, starting another cycle of rock formation. Sea level rose and fell cyclically depositing sediment.

Biological evolution on the other hand produced unique features. The evolution of any new trait or species was a phenomenon without precedent and without anticipation of being repeated in the future. A particular novelty, a particular evolutionary trend or pattern in a lineage evolved through a contingent sequence of events only once in the history of life.

His most famous book - The Origin of Species - reflects these thoughts as it ends:

"There is grandeur in this view of life, with its several powers, having been breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”