Page 259 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

241 solv- and/or liquids, have to is load supporting into plate the of plate end the near diver thus Local

Isostasy : topography of compensation. then area, (h) compensation like assumed of a effect the strength elastic an (D) elastic near especially the rigidly: bending)

highest one thicknesses whereby behave are the of of that rigidity The load. diver standing greatly, to Isostasy rigidity of the supporting material. a) Regional isostasy. Materials with
= Constant the of depth the constant: Constant for assumed estimate materials materials rigid; rigidity lithospheric is flexural the bends more behaves (resistance Regional

Pinln level the to is = or to areas. isostasy, somewhat flexural take compensation The supports the being D) rigidity b) flexural load. b)

+ to down column h,, used other local supporting words, the the therefore loads. plate (small material the
p.h, up column, + h, determined be on isostatic /oad board board. the

- 0) column, column vertical + can beneath assume 8.21a); other however, are subsurface the the same flexural depends on is directly below
phy = mantle +h, be Isostasy) In depending isostasy which board, weak the The of each
+ (p, air air water water crust crust mantle of each can simultaneously columns models (Fig. load. regional and to thin, of
p,h, the the the of‘the the the the the =h, (P/g) load the materials, area, regional of degree diving A thickness

= of of of of of of of (T) T (Regional Airy a broad topographic a board deflection. Isostasy rigidity, compensation flexed, distributing the load over a broader region.
P/g thickness thickness thickness thickness column vertical and below accommodate Earth a of model the to 8.22). elastic type of isostatic compensation
density density density density thickness equations for Flexure Most over Models 8.21b). by analogous (Fig. thicker smaller the Local
tou "oul I = i ll (p) Pratt directly (Fig. common determines A on no is
> h, E E two
a o isostatic bent board
ag as a a a total the to rigidity. A is is diver. a &) The there
where: The 2) the If the ing densities Lithospheric Both occurs flowing no distributed material. account that plate model the of the causes depends 8.21 FIGURE isostasy. Where rigidity are

thickness force

(p) and Pratt and Airy pressure; mantle isostatic upward compen- com- crust Notice of equa- by

Density for = P gravitational acceleration. weight of extra to achieve an isostatic thickened 8.20. height the two column, divided

8.19 relationships isostatic models. Mountains basin root exerts isostatic Airy as Fig. in times region,
FIGURE (h, h’) = g regions. The regions. The crustal hypotheses, Pure well as illustrated 8 to 5 each vertical
Model to continental both model. crust, form typically beneath each

Mantle thin crust, relative until just enough depth of water fills the continental normal of components Pratt the than continental the exhibit is regions of compensation by exerted constant:

Isostasy ‘Compensation Isostatic Continent to of mountains. exhibit Airy the oceanic and might elevated depth the (P) pressure is (g),

and 0) OS eg, g/cnP) Constant regions have pulls downward thick crust, relative often to closer with mountains, beneath total acceleration
Gravity sae E Depth of Airy = Air (o 3.3 of Compensation = weight regions regions by root relief. At 1) The

g OOO OOOO OOOO = isostatic model. Oceanic oceanic crust appropriate generally for down crustal true.
8 Pressure topographic gravitational
OQ acs Depth While is
Chapter Pratt Model & Airy Model ee (p equilibrium. Mountainous regions have by the sation pensation weighted the that the tions hold the

240 a) Sea Level- Constant b) Sea Level-. = Constant eer Airy 8.20 material beneath the thin balanced

= FIGURE is it
P/g P/g unti