Ernest Grogg, age 10 of East Liverpool, Ohio, for his question:
Where is the coldest part of the world?
For a long time, people thought that the world's coldest spot was somewhere in Siberia where records of 90 below zero were. often taken. Then mankind went to the frozen continent of Antarctica and a frosty day in Siberia..began to look like a balmy spring day. Without a doubt, the coldest spot in the world is somewhere in the middle of the south polar continent. And the coldest day would be in July, for south of the equator, winter is in full swing while we are enjoying the best of the summer.
For some time, the coldest Antarctic record stood at minus 100 degrees. The scientists of the International Geophysical Year were down there in this deep freeze. Then, of all things, the weather got even colder. The coldest day so far recorded on the cold continent dipped to minus 125 degree. Brrrs
Walter Rogers, age 11$ of Wichita, Kansas, for his question:
What is a concretion rock?
Once in a while, we find a lump of hard mineral embedded in softer limestone., sandstone or shale. The hard mineral may be iron oxides ca2ciuL.: carbonate or perhaps glossy black flint, In any cases it will be of different material from the bedrock. This buried lump of rock may be a concretion. It may be less than an inch long or any size up to several feet. It may be rounds oval or some fantastic geometric shape.
A concretion may be found deep below the surface, buried in the softer bedrock like a raisin in a bun. Naturally, we wonder how in the world it got there. Then we remember that sandstone chalk, shale and limestone are sedimentary rooks. Such rocks sere formed from the silt, sand and shells in muddy water. As this muddy mixture dries: small pebbles are embedded in the solid rock. But, if we guessed this to be the history of a concretion, we would be wrong.
The story of a concretion is far more exciting than that of a pebble dried in the mud, We find the clues to its history when such a stone is cut open. The hard mineral material is arranged in layers like the skin of an onion. Obviously it was formed by adding one overcoat upon another. In many cases the hard overcoats are wrapped around an ancient fossil.
The center, or nucleus of a concretion may be the actual remains or merely the imprint of a leaf, a fern frond! a dainty shell or a bone. Certain large concretions have been found built around entire fossil skeletons. In some cases the hard nodule is built merely around a grain of sand and sometimes there seems to be no nucleus at all.
At first sights the hard concretion seems to be a complete stranger to the rock around it. But when we examine the bedrock, we find that it has small traces of the concretion minerals within it. There may be traces of silica in chalk end limestone, traces of iron oxide or calcium carbonate in shale and sandstone. Somehow,, the traces of these hard minerals have managed to collect in one place to form a nodule.
The job was done, of course, by seeping water, As the sedimentary rocks formed, they were steeped in water and all sorts of minerals were dissolved. These dissolved minerals were carried from place to place and as the rock dried they were in the main evenly distributed. However, here and there, the mineral loaded water came upon a bit of foreign material perhaps a decaying fossil. Sometimes, this bat of foreign materiel brought about a chemical change in the mineral loaded wator. One or more of its minerals were deposited around the nucleus, Thin went on time after time until the concretion rock was built up layer upon layers