Earths outer layer if we consider physical properties and not chemistry is what

Earth's outer layer is called lithosphere- the word which originated from two Greek words lithos and sphaeros, meaning rocks and sphere respectively.

If we talk about physical properties of lithosphere it is the part of earth on which we are living. comprising the  uppermost part of the mantle and the crust, that is rigid solid and brittle.

Lithosphere can further be subdivided in different layers like crust, mantle, outer and inner core. Crust comprises the outermost layer of earth,

There are rocks of different types and densities found on earth, If we talk about continents, they are present of granite layer of crust. Crust is the only functional part of the earth's layers that enables the survival of life on it, and provides the living organisms with anchorage, shelter and food. Some important physical characteristics of lithosphere are:

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the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.