September 12, 2020

1. The Voyage of the Beagle

Darwin’s Voyage of the Beagle is an extremely good book — a travel book as well as a science book, well-written and well-arranged, long but consistently interesting. The voyage lasted five years (the Beagle left England in late 1831, and returned in late 1836). The main objective of the voyage was surveying the southern coasts of South America, so Darwin spent considerable time in Patagonia and Tierra del Fuego.

Darwin often left the Beagle, and took excursions by himself, or with a guide, or with a small group from the Beagle. He was a tireless explorer, covering vast distances on horseback or in a small boat, sometimes in wet, cold conditions, sometimes without food or water, sometimes in areas where a war was raging between natives and Europeans. Once he hired two guides who were

well-armed with pistols and sabers; a precaution which I thought rather unnecessary; but the first piece of news we heard was, that, the day before, a traveler from Monte Video had been found dead on the road, with his throat cut. This happened close to a cross, the record of a former murder.

Darwin faced not only dangers, but also inconveniences, such as rough lodgings:

Our resting-house was so dirty that I preferred sleeping outside: on these journeys the first night is generally very uncomfortable, because one is not accustomed to the tickling and biting of the fleas. I am sure, in the morning, there was not a space on my legs of the size of a shilling, which had not its little red mark where the flea had feasted.

Darwin found that country inns offered a limited menu:

On first arriving, it was our custom to unsaddle the horses and give them their Indian corn; then, with a low bow, to ask the senor to do us the favor to give us something to eat. “Anything you choose, sir,” was his usual answer. For the few first times, vainly I thanked providence for having guided us to so good a man. The conversation proceeding, the case universally became deplorable. “Any fish can you do us the favor of giving?” “Oh! no, sir.” “Any soup?” “No, sir.” “Any bread?” “Oh! no, sir.” “Any dried meat?” “Oh! no, sir.” If we were lucky, by waiting a couple of hours, we obtained fowls, rice, and farinha. It not unfrequently happened, that we were obliged to kill, with stones, the poultry for our own supper. When, thoroughly exhausted by fatigue and hunger, we timorously hinted that we should be glad of our meal, the pompous, and (though true) most unsatisfactory answer was, “It will be ready when it is ready.”

Far better was the meal prepared by Tahitians, when Darwin was hiking and camping with native guides in the mountains of Tahiti:

The Tahitians having made a small fire of sticks, placed a score of stones, of about the size of cricket-balls, on the burning wood. In about ten minutes the sticks were consumed, and the stones hot. They had previously folded up in small parcels of leaves, pieces of beef, fish, ripe and unripe bananas, and the tops of the wild arum. These green parcels were laid in a layer between two layers of the hot stones, and the whole then covered up with earth, so that no smoke or steam could escape. In about a quarter of an hour, the whole was most deliciously cooked. The choice green parcels were now laid on a cloth of banana leaves, and with a cocoa-nut shell we drank the cool water of the running stream; and thus we enjoyed our rustic meal.

Darwin was constantly collecting specimens. In Brazil, he collected 68 different species of beetle in one day.1 On the island of San Pedro off Chile, Darwin snuck up behind a fox, and killed it with his “geological hammer,” which he carried for collecting rock samples. “This fox [is] now mounted in the museum of the Zoological Society.”

Darwin doesn’t hesitate to describe situations where he himself plays an un-heroic role. For example, when he tries the bolas (balls tied to ropes, used to catch horses, ostriches, etc.), he catches his own horse:

The main difficulty in using either lazo or bolas is to ride so well as to be able at full speed, and while suddenly turning about, to whirl them so steadily round the head, as to take aim: on foot any person would soon learn the art. One day, as I was amusing myself by galloping and whirling the balls round my head, by accident the free one... caught one hind leg of my horse; the other ball was then jerked out of my hand, and the horse fairly secured. Luckily he was an old practiced animal, and knew what it meant; otherwise he would probably have kicked till he had thrown himself down. The Gauchos roared with laughter; they cried out that they had seen every sort of animal caught, but had never before seen a man caught by himself.

When he’s travelling on the Parana River, near the border of Uruguay and Brazil, Darwin says that fear of jaguars

quite destroyed all pleasure in scrambling through the woods. This evening I had not proceeded a hundred yards, before finding indubitable signs of the recent presence of the [jaguar], I was obliged to come back. On every island there were tracks.... On the Parana they have killed many wood-cutters, and have even entered vessels at night.

Darwin says little about the occult, but he does tell one story about foreknowledge. Darwin says that, in an earthquake, it’s dangerous to be in a room with the door closed. “The danger in an earthquake is not from the time lost in opening a door, but from the chance of its becoming jammed by the movement of the walls.” Darwin met a man in Chile who

mentioned a curious coincidence... he was playing at cards, when a German, one of the party, got up, and said he would never sit in a room in these countries with the door shut, as, owing to his having done so, he had nearly lost his life at Copiapó. Accordingly he opened the door; and no sooner had he done this, than he cried out, “Here it comes again!” and the famous shock commenced. The whole party escaped.

Notice how Darwin describes the story as a “coincidence,” though it’s surely more than a coincidence. That he would call it a coincidence tells us much about his way of thinking, his aversion for the occult. In this “coincidence,” Darwin was encountering the occult connectedness of the world, a connectedness that enables us to solve the greatest mysteries of the universe, including two mysteries that preoccupied Darwin, the origin of life and the origin of species.2

Darwin often discusses the animals he meets, such as Galapagos tortoises:

The inhabitants believe that these animals are absolutely deaf; certainly they do not overhear a person walking close behind them. I was always amused when overtaking one of these great monsters, as it was quietly pacing along, to see how suddenly, the instant I passed, it would draw in its head and legs, and uttering a deep hiss fall to the ground with a heavy sound, as if struck dead. I frequently got on their backs, and then giving a few raps on the hinder part of their shells, they would rise up and walk away; but I found it very difficult to keep my balance.

The word “Galapagos” means “tortoise.” The Galapagos Islands abounded with tortoises, lizards, and other reptiles. Darwin says, “There is no other quarter of the world where this Order [i.e., reptiles] replaces the herbivorous mammalia in so extraordinary a manner.” When Darwin visited New Zealand, he found that mammals were replaced there by flightless birds, such as the giant Moa, which went extinct around 1500 AD.

On Galapagos lizards:

This animal, when making its burrow, works alternately the opposite sides of its body. One front leg for a short time scratches up the soil, and throws it towards the hind foot, which is well placed so as to heave it beyond the mouth of the hole. That side of the body being tired, the other takes up the task, and so on alternately. I watched one for a long time, till half its body was buried; I then walked up and pulled it by the tail; at this it was greatly astonished, and soon shuffled up to see what was the matter; and then stared me in the face, as much as to say, “What made you pull my tail?”

The most famous animals that Darwin encountered were the finches of the Galapagos. These finches helped him to formulate his theory of evolution. The various finch species in the Galapagos seemed to have branched off from a common ancestor, and changed over time.

The most curious fact [Darwin writes] is the perfect gradation in the size of the beaks in the different species.... There are no less than six species with... graduated beaks.... One might really fancy that... one species had been taken and modified for different ends.

Different species of Galapagos finches, with different beaks

Darwin was astonished to find that different islands in the Galapagos Archipelago had developed different finch species: “It is the circumstance, that several of the islands possess their own species of the tortoise, mocking-thrush, finches... that strikes me with wonder.” Clearly the finch species were changing, adapting to different environments, they weren’t static/permanent. The Galapagos were the perfect place to see species evolving, they were an evolution laboratory, largely isolated from the rest of the world, largely untouched by man. Darwin spent about five weeks in the Galapagos.3

* * * * *

Darwin discusses SouthAmerican dogs who are raised with sheep, and become loyal guardians of sheep, protecting them from wild dogs: “A whole pack of the hungry wild dogs will scarcely ever (and I was told by some never) venture to attack a flock guarded by even one of these faithful shepherds.” Notice the fine distinction that Darwin makes between “scarcely ever” and “never.” Darwin was renowned for his intellectual honesty and fairness.

In the Falkland Islands, he encounters a duck or goose called a “steamer.” He says, “I am nearly sure that the steamer moves its wings alternately, instead of both together, as in other birds.” Notice that Darwin tells us his precise degree of certainty: “nearly sure.”

Darwin observes a small spider “elevate its abdomen, send forth a thread, and then sail away horizontally.... I thought I could perceive that the spider, before performing the above preparatory steps, connected its legs together with the most delicate threads, but I am not sure whether this observation was correct.” Thus, he openly admits that he’s not sure what the spider’s doing, even after observing it “repeatedly.”

Darwin is often content to frame a question, without attempting an answer. He’s fascinated by the natives in Tierra del Fuego, and he wonders how they can imitate European speech:

They could repeat with perfect correctness each word in any sentence we addressed them, and they remembered such words for some time. Yet we Europeans all know how difficult it is to distinguish apart the sounds in a foreign language.... All savages appear to possess, to an uncommon degree, this power of mimicry.... The Australians [have] long been notorious for being able to imitate and describe the gait of any man, so that he may be recognized. How can this faculty be explained? Is it a consequence of the more practiced habits of perception and keener senses, common to all men in a savage state, as compared with those long civilized?

Darwin is committed to truth, even on subjects that seem unimportant. He states his degree of certainty, and if he’s entirely uncertain, he leaves the question unanswered.

His honesty, simplicity, and humility were apparent to people who met him socially. James Bryce met Darwin when Darwin was near the end of his life. Bryce said,

The impression which his whole demeanor and conversation made was that of perfect candor and naturalness. There was nothing of what people call “self-consciousness.” Darwin left on every one who knew him the impression of a philosopher in that old sense of the word which makes it denote not only the love of wisdom and truth but the tranquility of mind, the calmness and peace, which devotion to truth brings. In him wisdom and the search for truth appeared to have had their perfect work, in forming a character, so beautiful in its earnestness, its modesty, its simplicity, its sweet serenity.

2. Extinctions

When Darwin was in South America, he found many bones of extinct species. “The whole area of the Pampas,” he wrote, “is one wide sepulcher of these extinct gigantic quadrupeds.... Besides those which I found during my short excursions, I heard of many others, and the origin of such names as ‘the stream of the animal,’ ‘the hill of the giant,’ is obvious.”

One of the large quadrupeds that went extinct was the horse.

Certainly it is a marvelous fact [Darwin writes] in the history of the Mammalia, that in South America a native horse should have lived and disappeared, to be succeeded in after ages by the countless herds descended from the few introduced with the Spanish colonists!

Darwin is astonished by the abundant evidence of extinct giants. What a difference between today’s fauna and yesterday’s mega-fauna!

It is impossible to reflect on the changed state of the American continent without the deepest astonishment. Formerly it must have swarmed with great monsters: now we find mere pygmies, compared with the antecedent, allied races.

What can possibly account for the extinction of the mega-fauna? How did all these mammals, who lived quite recently, become extinct?

The greater number, if not all, of these extinct quadrupeds lived at a late period, and were the contemporaries of most of the existing sea-shells. Since they lived, no very great change in the form of the land can have taken place. What, then, has exterminated so many species and whole genera? The mind at first is irresistibly hurried into the belief of some great catastrophe; but thus to destroy animals, both large and small, in Southern Patagonia, in Brazil, on the Cordillera of Peru, in North America up to Behring’s Straits, we must shake the entire framework of the globe.

The giant quadrupeds lived not only in South America, but all over the world.

It appears from the character of the fossils in Europe, Asia, Australia, and in North and South America, that those conditions which favor the life of the larger quadrupeds were lately co-extensive with the world: what those conditions were, no one has yet even conjectured.

Is it possible that the extinction of the mega-fauna is linked to the emergence of man? “Did man, after his first inroad into South America, destroy, as has been suggested, the unwieldy Megatherium and the other Edentata?”4 When the Maori came to New Zealand from Polynesia, they hunted the giant flightless birds (the moa) to extinction.

These extinctions are one of the chief puzzles in natural science. “Certainly, no fact in the long history of the world is so startling as the wide and repeated exterminations of its inhabitants.” Extinctions were a problem for theology: if each species was created by God, why did so many fail?

Charles Lyell, the geologist whom Darwin studied closely, wrestled with the extinction puzzle, and thought that extinctions might be caused by climate change. Climate is affected by the arrangement of land/water — in other words, by the size, position, and elevation of the continents. We know that much of what is now land was once water, and we know that much of the temperate zone once had a tropical climate. In the time of the dinosaurs, the world was warmer, the oceans more extensive. Lyell argues that this more tropical climate may have been caused by a different arrangement of land/water — less land in the polar and temperate regions, more in the tropical regions. As this situation changed, and more land arose in the polar and temperate regions, the climate of the earth as a whole became colder, possibly causing extinctions.5

Lyell was unaware of ice ages (the theory of ice ages was developed by Agassiz and others around 1850).6 Lyell was also unaware of the theory of Continental Drift (this theory was developed by Wegener around 1915). And Lyell was unaware of the asteroid that apparently caused the extinction of the dinosaurs (this theory was developed by Walter Alvarez around 1975).

On the other hand, none of these theories would have completely surprised Lyell: he knew that climate changed greatly over time, he knew the earth was subject to catastrophic events, and he knew that the arrangement of land/water changed over time. So he understood all three of these theories in their broad outlines, but he didn’t know the details, or when they’d be discovered, or by whom.

Lyell realizes that man can alter the climate: “The labors of man have, by the drainage of lakes and marshes, and the felling of extensive forests, caused... changes in the atmosphere.” As he grew older, did Lyell realize that coal-burning etc. could change atmosphere/climate?

There’s now far more “temperate land” in the northern hemisphere than in the southern hemisphere: “On comparing the extra-tropical lands in the northern and southern hemispheres, the former are found to be to the latter in the proportion of thirteen to one!” But it wasn’t always thus; the northern hemisphere was once more watery. Lyell speaks of, “the prevalence throughout the northern hemisphere of a great ocean, interspersed with small isles.”

Lyell distinguishes between an “insular climate” and an “excessive climate.” An excessive climate is found on large continents; in the summer, there’s excessive heat; in the winter, excessive cold. An insular climate has cooler summers, warmer winters; seasonal changes aren’t as dramatic, the climate is more equable.

Here in New England, an example of an insular climate is Nantucket Island, which has warmer winters and cooler summers than the mainland. Lyell argues that Siberia once had an insular climate, since it was partly covered by ocean; since winters were milder, it could support plants and animals that we think of as tropical. The skeletons of many large mammals, now extinct, have been found in Siberia.

Lyell writes,

The remains both of the animal and vegetable kingdom preserved in strata of different ages, indicate that there has been a great diminution of temperature throughout the northern hemisphere, in the latitudes now occupied by Europe, Asia, and America. The change has extended to the arctic circle, as well as to the temperate zone. The heat and humidity of the air, and the uniformity of climate, appear to have been most remarkable when the oldest strata hitherto discovered were formed.

Lyell says that NorthAmerican cities like New York and Quebec have an “excessive climate,” while European cities generally have an insular climate. The word “insular” is related to the word “insulated” — both come from the Latin word for “island.”

Imagine that you’re living in a house with no insulation. The summers would be hot, the winters cold. On the other hand, an insulated house has a more equable temperature. Europe has an insular climate, it’s insulated by the sea on its north side. On the other hand, North America has more land in the far north, so it has colder winters than Europe. “The lands to the north of Greenland cause the present climate of North America to be colder than that of Europe in the same latitudes.” The sea insulates from excessive heat and cold, while land conducts heat and cold.

Lyell writes,

There are insular climates where the seasons are nearly equalized, and excessive climates... where the temperature of winter and summer is strongly contrasted. The whole of Europe, compared with the eastern parts of America and Asia, has an insular climate. The northern part of China, and the Atlantic region of the United States, exhibit “excessive climates.” We find at New York... the summer of Rome and the winter of Copenhagen; at Quebec, the summer of Paris and the winter of Petersburg. At [Beijing] in China, where the mean temperature of the year is that of the coasts of Brittany, the scorching heats of summer are greater than at Cairo, and the winters as rigorous as at Uppsala.

London, being insulated by surrounding seas, is much warmer in the winter, and much colder in the summer, than Indianapolis; London has an average temperature in January of 40 F, versus just 28 F for Indianapolis, despite the fact that London is much further north (London’s latitude is 51, Indianapolis’ 39). In August, London’s temperature averages just 63, versus 75 for Indianapolis.

London’s climate is affected by the surrounding seas in general, and by the Gulf Stream in particular. The Gulf Stream prevents ice from accumulating in the seas north of England. Lyell writes,

That most powerful current, the Gulf stream, after doubling the Cape of Good Hope, flows to the northward along the western coast of Africa, then crosses the Atlantic, and accumulates in the Gulf of Mexico. It then issues through the Straits of Bahama, running northwards at the rate of four miles an hour, and retains in the parallel of 38°, nearly one thousand miles from the above strait, a temperature 10° F warmer than the air. The general climate of Europe is materially affected by the volume of warmer water thus borne northwards, for it maintains an open sea free from ice in the meridian of East Greenland and Spitzbergen, and thus moderates the cold of all the lands lying to the south.

Europe’s climate is also affected by Africa, which collects intense heat near the equator, then sends it into the atmosphere, where it eventually warms Europe. Lyell writes,

The surface being in this case exposed to the vertical, or nearly vertical rays of the sun, absorbs a large quantity of heat, which it diffuses by radiation into the atmosphere. For this reason, [European countries] derive warmth from Africa, “which, like an immense furnace... distributes its heat to Arabia, to Turkey in Asia, and to Europe.”

Thus, climate in one area affects climate in another area. A certain amount of cold may cause more cold, by a kind of “domino effect,” while a certain amount of heat may cause more heat. This raises the possibility of an Ice Age or a “Heat Age,” both of which have existed in the past.7

Now let’s compare the climate of the Northern Hemisphere with that of the Southern Hemisphere. As we move closer to the poles (higher latitudes), we find that the Southern Hemisphere is colder, perhaps because it doesn’t have large land masses to absorb the sun’s rays.8 Darwin says that at the Strait of Magellan, if you climb to a height of 3500 feet, you find perpetual snow. But in the Northern Hemisphere, you would need to go 14° nearer to the pole to find perpetual snow at 3500 feet (at the equator, you need to climb to about 16,000 feet to find perpetual snow).

A lower snow-line, Darwin says, means more glaciers descending to the sea. In South America, Darwin found “immense glaciers” descending to the sea at the latitude of Paris. “Great masses of ice frequently fall from these icy cliffs, and the crash reverberates like the broadside of a man-of-war, through the lonely channels.”

* * * * *

In his Voyage of the Beagle, Darwin seems interested in the extinction of large mammals, which occurred quite recently, during the so-called Quaternary Period. But Lyell seems to be aware not only of a recent extinction event, but also of a much earlier extinction event, the one that destroyed the dinosaurs, sometimes called the KT Extinction. Lyell speaks of, “the abruptness of the transition from the organic remains of the secondary to those of the tertiary epoch,” and he tentatively suggests that “the interval between the chalk and tertiary formations constituted an era in the earth’s history, when the passage from one class of organic beings to another was, comparatively speaking, rapid.”9

© L. James Hammond 2020
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1. “I may mention, as a common instance of one day’s (June 23rd) collecting, when I was not attending particularly to the Coleoptera [i.e., beetles], that I caught sixty-eight species of that order.... Thirty-seven species of Arachnidę, which I brought home, will be sufficient to prove that I was not paying overmuch attention to the generally favored order of Coleoptera.”

Darwin was often seasick on the Beagle voyage. Did this, and the other hardships he experienced on the voyage, contribute to his later health problems? In my view, his later health problems had a psychological cause, they were the body’s protest against stress and overwork — it’s a case of “the body saying No.” (In an earlier issue, I discussed a book called When the Body Says No: Exploring the Stress-Disease Connection.)

According to Wikipedia,

While developing [his theory of evolution], Darwin became mired in more work. Still re-writing his [Voyage of the Beagle], he took on editing and publishing the expert reports on his collections. [He] agreed to unrealistic dates with the publisher.... As Darwin worked under pressure, his health suffered.... William Whewell pushed Darwin to take on the duties of Secretary of the Geological Society. [He can’t say No, so finally his body says No.] The strain took a toll, and by June [1838] he was being laid up for days on end with stomach problems, headaches and heart symptoms. For the rest of his life, he was repeatedly incapacitated with episodes of stomach pains, vomiting, severe boils, palpitations, trembling and other symptoms, particularly during times of stress, such as attending meetings or making social visits. The cause of Darwin’s illness remained unknown, and attempts at treatment had only ephemeral success.

In my chapter on genius, I wrote, “Genius often has a tendency toward illness. Examples of geniuses who were chronically ill are Epicurus, Pascal, Lichtenberg, Schiller, Leopardi, Darwin, Nietzsche and Proust.” back

2. Important discoveries are often made by investigating anomalies. This earthquake story is anomalous, or as Darwin says, “curious.” In general, everything occult is anomalous, hence the occult is the most fertile field for discoveries. It’s also the field that, more than any other field, academics dismiss with contempt. back
3. One might ask, How did any animals reach the Galapagos? The Galapagos are about 600 miles west of Ecuador. Birds could have flown, other animals could have floated (“rafted”) on logs/vegetation. Wikipedia speaks of “large rafts of floating vegetation such as are sometimes seen floating down major rivers in the tropics and washing out to sea, occasionally with animals trapped on them.... Colonization of land masses by plants can also occur via long-distance oceanic dispersal of floating seeds.”

If only a few bird species reached the Galapagos, they could evolve to fill various niches; this is what happened with Darwin’s finches (“from an original paucity of birds in this archipelago, one species had been taken and modified for different ends”). It would be as if a plumber went to a small town, a town that had no plumbers, no electricians, and no carpenters. So the plumber gradually became the town’s electrician and the town’s carpenter, as well as the town’s plumber.

In addition to animals and plants, stones can also travel long distances, and reach remote islands. When Darwin visited a group of coral islands (the Keeling Islands), he was surprised to find a stone that seemed out of place in this coral world. He wondered if it could have been carried in the roots of floating trees, like animals carried on floating trees. Then he found a passage in a travel book that described how rocks carried long distances by trees were highly valued by the natives on coral islands, since they were the only hard rocks in a world of soft rocks, and therefore they could be used for sharpening, for tools, for weapons, etc. “Stones may often be thus carried,” Darwin writes; “and if the island on which they are stranded is constructed of any other substance besides coral, they would scarcely attract attention, and their origin at least would never be guessed.”(Voyage of the Beagle, Ch. 20) back

4. Darwin often uses scientific terms that are now obsolete; “Edentata” is one such term. According to Wikipedia, “the order Edentata (meaning toothless, because the members do not have incisors and lack, or have poorly developed, molars)... was found to be a polyphyletic grouping whose New World and Old World taxa are unrelated, and it was split up to reflect their true phylogeny.”

Wikipedia also says, “Megatherium was a sloth [that] became extinct around 12,000 years ago during the Quaternary extinction event, which also claimed most other large mammals in the New World. The extinction coincides with the settlement of the Americas, and a kill site where a [Megatherium] was slaughtered and butchered is known, suggesting that hunting could have caused its extinction.”

Perhaps early man killed more animals than he needed for his own sustenance. The instinct to hunt and kill is a strong one, and not just in man. I’ve often heard people say, “I had 15 chickens, but a weasel [or a fisher, or some other carnivore] killed all of them. He didn’t eat them, he just killed them and piled them up.” back

5. Lyell says that if land is transferred from “the torrid zone to the temperate and arctic regions of the northern hemisphere, there might be so great a refrigeration of the mean temperature in all latitudes, that scarcely any of the pre-existing races of animals would survive.... A great fluctuation in the mean temperature of the earth [is] the most influential cause which can be conceived in exterminating whole races of animals and plants.”(Principles of Geology, Ch. 8) We now know that continents move around as a result of Continental Drift, which happens so slowly that it seems unlikely to cause extinction, it seems more likely to cause modification of species (evolution). However, Ice Ages can come and go in a relatively short space of time, so perhaps the climate theory of extinction has merit. Another extinction-theory that has merit is asteroid-impact, but it was difficult for Lyell to conceive of this.

Lyell seems to guess correctly that Continental Drift takes place at a slow and steady pace: “a given amount of alteration in the superficial inequalities of the surface of the planet always requires for its consummation nearly equal periods of time.” And Lyell seems to guess correctly that the earth’s internal heat is steady: “we ought still to be very reluctant to concede on slight evidence that the internal heat is variable in quantity.” He’s skeptical of the argument, advanced by some geologists, that the earth was originally hot, and has been cooling ever since. back

6. Lyell was unaware of Agassiz’s IceAge theory when he wrote the first edition of his Principles of Geology. He became aware of Agassiz’s theory soon after, and it seems that he was partly converted. back
7. “No great disturbance,” Lyell writes, “can be brought about in the climate of a particular region, without immediately affecting all other latitudes, however remote. The heat and cold which surround the globe are in a state of constant and universal flux and reflux.” back
8. “The mean temperature of higher latitudes in the southern hemisphere is,” Lyell writes, “...for the most part lower than that of the same parallels in the northern.”

Darwin noted that the Southern Hemisphere has more ice, but also more luxuriant vegetation; paradoxically, it has ice in proximity to luxuriant vegetation. “In the Southern Ocean,” Darwin writes, “the winter is not so excessively cold, but the summer is far less hot, for the clouded sky seldom allows the sun to warm the ocean, itself a bad absorbent of heat; and hence the mean temperature of the year [is] low. It is evident that a rank vegetation, which does not so much require heat as it does protection from intense cold, would approach much nearer to this zone of perpetual congelation under the equable climate of the southern hemisphere, than under the extreme climate of the northern continents.” back

9. Notice that Lyell uses the terms “secondary” and “chalk” as synonyms. Chalk refers to the Cretaceous Period (“Cretaceous” comes from the Latin creta, meaning “chalk”). The Cretaceous Period lasted from about 145 million years ago to 66 million years ago. The Cretaceous Period ended with the KT Extinction; the KT Extinction is the boundary between the Cretaceous and the Tertiary. “KT” means “Cretaceous Tertiary,” Cretaceous being spelled with a K in the German manner.

Darwin speaks of, “the Secondary epochs, when lizards, some herbivorous, some carnivorous, and of dimensions comparable only with our existing whales, swarmed on the land and in the sea.”(Voyage of the Beagle, Ch. 17) back