1. The two major causes of desertification are the climate variations and the human activities. The desertification is a process that is a growing concern in the world, as the deserts have been spreading out more and more. One of the reasons are the climate variations. The changes in the precipitation patterns have resulted in reduced precipitation levels at certain places, resulting in the dying out of the vegetation and gradually being replaced with barren land dominated by sand or rocks. The other major cause is the human activity. The humans have been destroying lot of the vegetation because of their own needs, as well as using the waters in the arid and semi-arid regions extensively, resulting in barren landscape with destroyed soil, quickly becoming desert or semi-desert.
2. The basic mechanism of desertification is the change in climate, which is triggering the reactivation of the dormant sand dunes. The climate is constantly changing, and that is not something new, and while it may have positive effects at certain places, it has negative ones in others. When the precipitation levels drop significantly at certain places, the vegetation is starting to die out, and to be replaced by a desert one. The soil is also getting downgraded significantly. This enables the winds to be much bigger factor in shaping the landscape. They start to pick up small particles from the barren land and disperse them, and as they do they create sand dunes gradually, creating a desert.
3. The adverse effects for the humans from the desertification are numerous. With the desertification, the areas become much less suitable for living, in certain occasions almost impossible. The soil is destroyed, thus the agriculture and farming of animals can not be performed, meaning that food can not be produced. The water reserves go significantly down, so there's not enough water for drinking or for the other needs of the humans. The winds are become a big problem, they are much stronger and often cause sand storms, which can even be deadly if someone is caught in the open. The climate is very harsh, the temperatures are very high and it is very dry, or if it is a cold desert, it will have both very high and very low temperatures, depending on the period of the year.
Answer:
mountains, valleys and plateaus
Explanation:
The seashore is an inhospitable place for marine animals to live. Seawater has much less temperature variation throughout the year than air. In other words, during the summer in New York it can be 98˚F but the sea isn’t much warmer than 75˚F. In the depths of winter it can be –10˚F on land, but the water will be 48˚F. Animals that spend all their lives out at sea have a fairly steady environment. Those that are exposed to air at low tide, may face broiling hot temperatures in summer and freezing cold temperatures in winter. They may be soaked in fresh water when it pours with rain, and pounded by rough waves during a storm. Animals that can survive on the shore have to be tough! The higher the animals live up the shore the longer they are likely to be exposed to the land environmental conditions. On rocky shores this leads to bands of animals that are the best adapted to being exposed for that period of time. These bands are called tidal zones.
Answer:
A, B and D
Explanation:
The continental crust contains igneous, sedimentary and metamorphic rocks. Along convergent plate boundaries, the continental crust gets renewed with igneous rock providing more rock to be made into sedimentary rock. The sedimentary rock can then continue to sink into the crust becoming metamorphic. Due to this variety of types of rock, the minerals can be diverse, including sodium, potassium, aluminium and calcium. Continental crust is also much thicker, up to 70km.
Answer:
Correlation
Explanation:
Correlation simply means matching rocks or strata's of the same age. This rock units or sedimentary strata's may be matched from same region or even different continents.
In correlation the major task is to establish time equivalency of various rocks or sedimentary strata's.
In correlation of rock unit or sedimentary strata, Geologist looks at the physical continuity. For example a sedimentary strata from a region having a particular sequence of rock or sedimentary strata . That same pattern of sequence may be found in another region . With the similarity in the sequence stratigraphy ( sediment layering), Geologist can infer the similarity in age of both strata's.
Fossil contents present in different strata; if similar fossil contents found in different regions, geologist can determine the age similarities.
The first picture indicates strata correlation using fossil similarities while the second picture uses the physical continuity like lithology to correlates strata's