Plock

Plock, or PLOTSK, a government of Russian Poland, on the right bank of the Vistula, having the Prussian provinces of West and East Prussia on the N. and the Polish governments of Lomza on the E. and Warsaw on the S. Its area is 4160 sq. m. Its flat surface, 350 to 500 ft. above the sea-level, rises gently towards the north, where it merges into the Baltic coast-ridge of the Prussian lake district. Only a few hills reach 600 ft. above Table Of Pliocene Formations.

Stages.

| 

England.

| 

Belgium

and

Holland.

| 

Rhone Basin.

| 

Languedoc

and

Roussillon.

| 

Italy.

| 

Eastern

Europe.

| 

Other Countries.  
  
---|---|---|---|---|---|---|---  
| 

Cromer Forest

| | | | | |   
| 

Bed.

| | | | | |   
| 

Fluvio-marine

| 

C 1 a y s o f

| 

Marls of St

| 

Durfort beds

| 

Sands of Val d'Arno.

| 

Upper

| 

Marine beds of  
  
Sicilian.

| 

N o r w i c h

| 

Campine.

| 

Cosme.

| 

with Elephas 

| 

Limestones of Paler-

| 

Paludina

| 

Entre Rios.  
  
| 

crag.

| 

Amstelian.

| 

G r a v e 1 s of

| 

meridionalis. 

| 

mo and clays with

| 

(Vivipara)

| 

Volcanic tuffs of  
  
| 

Red crag of

| | 

Chagny.

| | 

northern mollusca.

| 

beds.

| 

S. Sumatra.  
  
| 

Suffolk.

| | 

Conglomerates

of

| | | |   
| | | 

Conglomerates

| 

Marls of Val d'Arno

with Mastodon 

| |   
  
Chambaran.

Sands of Tre-  
  
| | 

Poederlian.

| 

v o u x and

| 

of Montpellier

| 

arvernensis. 

| | 

Petroleum-bearing  
  
Astian.

| 

Base of Red

crag.

| 

Scaldisian

sands with

| 

Mollon.

Travertine of

| 

and Fourres.

Sands of Rous-

| 

Yellow sands of Asti,

Plaisantin, Monte

| 

Middle

Paludina

| 

beds of Sumatra.

Marine sands of  
  
| | 

T r o p h o n 

antiquum. 

| 

Meximieux.

| 

s i 11 o n with

Mastodon 

arvernensis. 

| 

Maria and Tuscany.

Conglomerates of

Castrovillari.

| 

beds.

| 

Moghara and

Mokatta.  
  
| | 

Sands with

| 

Marine marls

| 

Yellow sands of

| | | 

Marine beds of  
  
Plaisancian.

| 

Coralline crag.

Lenham beds.

| 

Isocardia 

car. 

Diestian

sandstones.

| 

of Bresse,

Hauterives.

Congeria beds

of Bollene.

| 

Montpellier.

Blue marls of

Millas.

| 

Blue marls of Pia-

cenza, Bologna,

and Vatican.

| 

Lower

Paludina

beds.

| 

Florida.

Lacustrine beds of

Rocky Moun-

tains.  
  
## Life of the Pliocene Period

Sir C. Lyell defined the Pliocene strata as those which contained from 36-95% of living marine molluscs. This rule can no longer be strictly applied to the widely scattered marine deposits, and it is of course inapplicable to the very numerous formations of lacustrine and fluviatile origin. On the whole the marine organisms are very like their living representatives, and there is often practically no specific difference; Nassa, Voluta, Chenopus, Dentalium, Fusus, Arca, Pecten, Pectunculus, Panopoea, Cyprina and Mactra may be mentioned among the marine genera; Congeria (Dreyssensia), Auricula, Paludina, Melanopsis and Helix  are found in the lacustrine deposits. One of the most interesting facts exposed by the study of the mollusca is the gradual lowering of the temperature of Europe during the period. In Britain the early Pliocene was, if anything, warmer than at present, but the percentage of northern forms ascends steadily through the higher beds, and finally arctic forms, such as Buccinum groenlandicum, Trichopteris borealis, Mya truncata, Cyprina islandica, &c., appear on the coasts of Norfolk and Suffolk, and some of the northern species even reached the Mediterranean (Sicily) at the close of the period. The flora exhibits the same gradual change, the large palms and camphor trees disappeared from Europe, the sabal palm lingered in Languedoc, and Chamerops humilis lived about Marseilles until the end; the sequoias and bamboos held on for some time, and the aspect of the vegetation in mid-Pliocene times was not unlike that of Portugal, Algeria and Japan of to-day. Not a few species that dwelt in Pliocene Europe are found in the forests of America. The flora of the Cromer forest beds is very like that of the same district at the present time. The mammals of the British Pliocene show a curious blending of northern and southern forms; they include Machaerodus (the sabre-toothed lion), hyenas, dogs, fox, wolf, glutton, marten, bears, Ursus arvernensis and the grizzly and cave bear, seals, whales, dolphins, bisons, musk ox, gazelle, the red deer and many others now extinct, the roebuck, pigs and wild boar, hippopotamus, hipparion and horse (Equus caballus and E. stenonis), several species of rhinoceros, tapir, hyrax, elephants (Elephas meridionalis and E. antiquus), several mastodons, squirrel, beaver, hare, mice, voles, &c. The mastodon disappeared from Europe before the close of the period, but lived much longer in America. No generally accepted fossil man has been found in the Pliocene; Pithecanthropus erectus, found by E. Dubois in Java, is the nearest to the human type. Monkeys, Macacus and Semnopithecus, occur in the Pliocene of Europe. At this time the Pliocene mammals of North America were able to migrate into South America, and a few of the southern forms travelled northwards.

the sea, while the broad valley of the Vistula has an elevation of only 130 to 150 ft. In the west (district of Lipno) broad terraces, covered with forests, small lakes and ponds, and very poor in vegetation, descend from the Baltic lake-district towards the plains of Plock; and in the central district of Mlawa extensive marshes fill the upper basin of the Wkra. The Vistula borders the government on the south, almost all the way from Warsaw to Thorn, receiving the Skrwa and Wkra. The Drweca, or Drewenz, flows along the north-west boundary, while several small tributaries of the Narew drain the north-eastern district of Ciechanow. Peat-bogs, used for fuel, and marshes containing bog-iron, fill many depressions in the north, while the more elevated parts of the plains are covered with fertile clays, or a kind of "black earth." Lacustrine post-Glacial deposits fill all the depressions of the thick sheet of boulder clay, with Scandinavian erratic boulders, which extends everywhere over the Tertiary sands and marls - these last containing masses of silicated wood and lignite. Layers of gypsum are found in the hills beside the Vistula.

The estimated population in 1906 was 619,000. About onethird are Jews and 36,000 Germans. The government is divided into seven districts, of which the chief towns are Plock, Ciechanow, Lipno, Mlawa, Prasnysz, Rypin and Sierpc. Agriculture is the chief industry. The principal crops are rye, oats, barley, wheat and potatoes; beetroot is cultivated for sugar, especially on the large estates of the west, where modern machinery is used. Gardening and bee-keeping are extensively practised. In the north the property is much divided, and the landholders, very numerous in Ciechanow, are far from prosperous. The forests have been lavishly cut, but Plock is still one of the best wooded governments (20%) in Poland. Other occupations are provided by shipping on the Vistula, mining and various domestic industries, such as the fabrication of wooden cars, sledges and wheels, and textile industry. The manufactures include flour-mills, saw-mills, sugar factories, distilleries, tanneries, breweries, agricultural implement works, match factories and ironworks. There is some export trade, especially in the Lipno district; but its development is hampered by lack of communications, the best being those offered by the Vistula. The railway from Warsaw to Danzig, via Ciechanow and Mlawa, serves the eastern part of the government.

After the second dismemberment of Poland in 1793, what is now the government of Plock became part of Prussia. It fell under Russian dominion after the treaty of Vienna (1815), and, in the division of that time into five provinces, extended over the western part of the present government of Lomza, which was created in 1864 from the Ostrolenka and Pultusk districts of Plock, together with parts of the province of Augustowo.