156 



SCIENCE. 



Globe," published in 1857) and thus constitute great circles 

 from the Arctic to the Antartic circles, along which (per- 

 haps from the earth's crust being thinner than in the mid- 

 dle of continents) important seismic phenomena, such as 

 volcanic and earthquake action are frequent and abundant. 



Demonstration. — Elevating the north pole of the globe 

 2 3K°> an d bringing the straits of Macassar and of Bali* to 

 the eastern horizon, we find the wooden horizon mark the 

 general trend of Asia from the volcanoes of Java and Celebes, 

 passing through the volcanic regions of Japan, Kuriles, 

 and Kamchatka, and skirting the Japan warm stream. On 

 the opposite side of the globe this great circle passes 

 from Alaska to the basaltic region of Lake Superior, then 

 through South Carolina and the Bahamas to the earthquake 

 region of Caraccas, etc., explaining the convulsion in South 

 Carolina of 1811-12, just before the destruction of La 

 Guayras and Caraccas. Revolving the globe from west to 

 east 72°, or i-5th of 360 , we bring the coast of Africa to 

 the horizon ; 72 more will give the trend of South 

 America, passing between Madeira proper and Porto Santo, 

 where Lyell observed a continental difference, especially 

 among the mollusks, as well as the seismic force ade- 

 quate to elevate the British coast (Lyell says in glacial 

 epoch) at least 600 feet, and Scandinavia, in historic times, 

 at some points five feet per century, total as much as 700 

 feet (see Lyell's " Principles," vol. I., p. 133.) On the 

 other side ef the globe it may have furnished the dynamics 

 of some volcanoes in Japan and Solomon's Archipelago, as 

 well as the earthquakes of New Zealand near Cook's 

 Straits. The trend of North America, just 72 west of the 

 above, passes from a volcanic region between Mexico and 

 Central America, along between the Appalachians, which it 

 raised, and our Atlantic seaboard, nearly parallel to the 

 Gulf Stream, and up to the Geysers and volcanoes of Ice- 

 land, coming round by the Field of Fire (Baker) on the 

 Caspian,' and through the ancient volcanic trap of Hindos- 

 tan, consequently is older than the South American trend. 

 The last or fifth trend either separated Australia from New 

 Zealand, or more probably brought the latter up recently, 

 as in it we find quaternary formations, such as the gigantic 

 Dinornis. 



III. — Third subdivision of 'the law. — An addition to the 

 dynamics of land-forming is found in there being for each 

 northern continent two foci of consolidation, which may 

 have resulted from shrinkage causing depression of adjoining 

 seas or seismic elevation of the plastic crust. The northern 

 focus, when two exist, is near the continental median line 

 and arctic circle ; the other occupies the geographical 

 centre of the continent. Concentric circles around these 

 foci not only mark important additions to the land and oro- 

 graphy of each continent, but especially pass as they en- 

 large from the areas of older geological formations to those 

 of newer. 



Demonstration. — A radius of 24 from the geographical 

 central focus often marks the outline of the continent 

 proper, while that of 36 embraces usually some of the ad- 

 joining islands, leaving out perhaps some peninsulas. 

 Between these two circles we find almost exclusively ceno- 

 zoic formations (tertiary), and outside of 36 in the three 

 southern continents quaternary. The details of North 

 American geology must suffice in an abstract, designating 

 for the other continents simply the position of the foci. 

 The northern focus for North America is in Boothia Felix. 

 With a radius of 24 from that point we reach the southern 

 point of the V shaped area near Lake Superior, as laid 

 down by Prof. Dana at p. 140 of his " Manual," where the 

 arch:ean meets the paleozoic. A more extended radius 

 passes through the coal of northern Iowa, of Michigan, 

 New Brunswick, and Newfoundland. A radius of about 

 29 -30 tfives us the mesozoic of Kansas and the Triassic (a 

 red sandstone with bird tracks) of Connecticut and Massa- 

 chusetts. 



Removing our center to the west shore of Lake Superior, 

 a radius of n° to 12'' gives us Silurian (Lower and Upper; 



* At these straits, though only about fifteen miles across, Wallace 

 found as great a difference between the flora and fauna as if they had 

 been a thousand miles apart, nearly all the animals south-east of that line 

 being marsupial, while northwest the chief type was and is carnivorous. 



from Niagara to near Springfield, O., Lexington and Frank- 

 fort, Ky., Nashville, Tenn., dominating at least the eastern 

 half of the circle, while the west was still under water. A 

 radius of 12° to 13° marks the Applachian and other coal 

 fields from north of Harrisburg, southwest through Tusca- 

 loosa, Ala., to Arkansas and Texas. A radius of 15 

 is Mesozoic, curving from the Cretaceous of Utah and Col- 

 orado through that of Arkansas and Tennessee to that of 

 New Jersey. A radius of 24 outlines the continent from 

 Cape Breton and Cape Sable to the Golden Gates; while 

 with from 18 to 24 we pass through the marine Tertiary 

 of Nevada, California, Northern Mexico, Texas, Louisiana, 

 Mississippi, Florida, Georgia, South and North Carolina, 

 Maryland and New Jersey to Martha's Vineyard and Barn- 

 stable, Mass. The circle of 36° embraces Yucatan and 

 Honduras; reaching to near Lake Nicaragua it encloses 

 several islands near our Pacific Coast and takes in part of 

 Alaska, as well as a portion of Greenland. 



The northern focus for Europe is in Scandinavia, Lat. 68° 

 N., Long. 22 E.; the geographical and later centre is in 

 Lat. 49^° N., Long. 20° E. 



The northern focus for Asia is in about Lat. 71° N., Long. 

 99 E. ; the centre is in same Long., and in Lat. 51° N. 



For South America the centre is on the Tropic of Capri- 

 corn, in about Long. 65 W. 



For Africa the centre is at St. Thomas' Island, where the 

 Magnetic Equator of dip crosses the terrestrial Equator. 



For Australia the centre is on the Tropic of Capricorn, 

 Long. 148° E. 



These are approximate, and may require slight modifica- 

 tions. 



IV. — Fourth Subdivision of the Law. — Besides these three 

 modifying influences, toward the close of the Mesozoic and 

 beginning of the Cenozoic, the Western Alps became a 

 dynamic focus, reaching, according to Elie de Beaumont, 

 their present height during the Miocene Period or at its 

 close, while the eastern Alps reached their present height 

 during the Pliocene. Mount Rosa is nearly, if not quite, 

 the geographical centre of the entire dry land on the globe; 

 and the Alps connect with the Himalayas and Andes of 

 similar geological age by a great circle or belt of immense 

 seismic activity. 



Demonstration. — A radius of 9 from Mt. Rosa defines ac- 

 curately the Miocene Tertiary on the east coast of England, 

 also in the middle of Denmark; through Prussia it is Eo- 

 cene, but Miocene again in Austria, Calabria, Sicily, Al- 

 giers and Central Spain. With a radius of 36 from Mt. 

 Rosa, we describe a curve from the Miocene of the eastern 

 flanks of the Urals to that of Spitzbergen and Greenland; 

 contrasting this radius somewhat, we follow the Carboni- 

 ferous and Peruican rocks of the Urals to Spitzbergen. 

 The great circle pointed out as passing from the Alps to 

 the Himalayas and Andes marks chiefly Tertiary regions. 



Summary. — The dynamics of land forming would seem, 

 from the foregoing demonstrations, to comprise first a lon- 

 gitudinal force, scarcely if at all seismic, adding to conti- 

 nents chiefly by aqueous depositions, as each northern con- 

 tinent, near the termination of the median line, has a large 

 river delta. Secondly, there is an Arctic-Antartic force, 

 mostly along continental coast lines, and connected with 

 active seismic phenomena of elevations and depressions; 

 apparently from these being thinner portions of the earth's 

 crust than at continental medial elongations. Thirdly, in 

 each continent there are radii and circles connected with 

 one or two important foci, which have not only aided in 

 defining the geographical limits of each continent, but also 

 in bringing geological deposits in successive curves of in- 

 crease to or near the surface; possibly because the wave 

 impulse directly under the plastic focus sends its molten 

 contents to equidistant circles beneath the plastic crust. 

 Lastly, the geology of each continent has also been some- 

 what modified, especially in cenozoic times, by the Alpine 

 central focus (or terminal axis from the centre) of the dry 

 land hemisphere. 



As corollaries, attention may be called to two additional 

 great circles of activity which are secondaries to that phase 





