Millions of years ago when the earth was young, the climate was hot and damp, eve near the North and South Poles. The land was covered with thick forests in which the only living things were reptiles, large insects, and other low forms of animal life.
In the forests, there were none of the beautiful trees we see today. Instead, there were plants such as ferns, reeds, and grasses which grew as tall as our tallest trees. Because the climate was hot and damp, the plants grew very fast, especially in the swampy places. As each plant died and fell to the ground, another plant took its place. Then, it too died and fell. In this way, the ground became covered with a thick layer of dead plants.
In the swamps, this thick layer was covered with water and dirt washed down form higher ground. Then, other layers was formed and they, in turn, were covered with water and dirt. The water and dirt were so heavy that they pack down, or compressed, these layers. After many millions of years, there lay, buried under the dirt and water, many layers of what had one been plants growing in the bright sunshine. Then, the a surface of the earth changed so slowly that if you had been living then, you would not have noticed any changes during your whole lifetime. The sea flowed over the land many times. Under the bottom of the sea, the layers of dead plants were compressed until they were changed into coal.
Other changes took place also. For a long time, ice covered part of the earth, new mountains rose and new valleys and plains were formed. Our coal is found today in some of those mountains, valleys and plains.
What was the weather millions of years ago?
It was hot and dark.
The temperature was high but the weather was not humid.
The weather was hot and the moisture was high.
It was hot and arid.