Crevasse formation

Applications of fracture mechanics to ice. There are many natural examples, such such as the fracture in lake ice and in ice shelves (ice sheets that extend over water), crevasse formation in glaciers, and fracture in sea ice and these may be used as natural examples in terrestrial ice. ... 

Seismic Sources from Landslides and Glaciers, Fig. 29 Crevasse formation due to thickness adaption to increasing... 

The acid hydrolysis of silicates and carbonates that arises from the dissociation of CO2 in solution is known as carbonation (Equations (4) and (5)). Carbonation only occurs in a restricted number of subglacial environments, because ingress of atmospheric gases to these water-filled environments is restricted. It largely occurs in the major arterial channels at low flow, particularly near the terminus, and at the bottom of crevasses and moulins that reach the bed. Sediment is flushed rapidly from these environments, and there is little time for the formation of secondary weathering... 

The dominant types of cementation in the Zia Formation are pedogenic and phreatic. By definition, the spatial distribution of pedogenic carbonate is a function of the spatial distribution of palaeo-sols, which is a function of facies architecture and the length of time a particular surface was exposed. Most pedogenic carbonate in the Zia Formation is poorly developed, discontinuous and associated with finer-grained sediments in overbank fines (OF), crevasse splay (CS), and interdune (ID) facies associations (see Table 1 Fig. 6). Unlike discontin-... 

Figure 32 shows a space-filling three-dimensional crystal model [42] with closely packed (001) facing down. It is seen that there are holes far down into the bulk and similar channels run along [010] (hidden in Figure 32). It can be seen at the forms 100 to the left and to the right that the molecules arrange in such a way that they leave wedges which are not easily filled and which run down the bulk. Therefore, it appears that the formation of hills and crevasses is an obvious choice. The molecules have a chance to partially rotate around the b axis into free space while reacting photochemically. As...

The primary isocyanate reactions discussed earlier in Chapter 1 are exothermic and proceed in principle without reaction accelerators. The extreme reaction rates required in many of today s sophisticated polyurethane products, however, necessitate the employment of suitable catalytic systems. This is particularly true for one-shot polyurethane RIM where not only do the reactions have to be very fast but also a proper balance has to be established between the simultaneous reactions, in particular the polymerization reactions (polyol/isocyanate) and the foaming reaction (water/isocyanate). This balance is of extreme importance for the production of foam without collapse, caused by insufficient polymer strength at the end of gas evolution, or crevassing, caused by too slow gas formation or too fast gelation. 

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