This idea of _stratification_, like the cake layers, was already a familiar one to the geologists by Schliemann’s time. They could show that their lowest layer of rock was oldest or earliest, and that the overlying layers became more recent as one moved upward. Schliemann’s digging proved the same thing at Troy. His first (lowest and earliest) city had at least nine layers above it; he thought that the second layer contained the remains of Homer’s Troy. We now know that Homeric Troy was layer VIIa from the bottom; also, we count eleven layers or sub-layers in total. Schliemann’s work marks the beginnings of modern archeology. Scholars soon set out to dig on ancient sites, from Egypt to Central America. ARCHEOLOGICAL INFORMATION As time went on, the study of archeological materials--found either by accident or by digging on purpose--began to show certain things. Archeologists began to get ideas as to the kinds of objects that belonged together. If you compared a mail-order catalogue of 1890 with one of today, you would see a lot of differences. If you really studied the two catalogues hard, you would also begin to see that certain objects “go together.” Horseshoes and metal buggy tires and pieces of harness would begin to fit into a picture with certain kinds of coal stoves and furniture and china dishes and kerosene lamps. Our friend the spark plug, and radios and electric refrigerators and light bulbs would fit into a picture with different kinds of furniture and dishes and tools. You won’t be old enough to remember the kind of hats that women wore in 1890, but you’ve probably seen pictures of them, and you know very well they couldn’t be worn with the fashions of today. This is one of the ways that archeologists study their materials. The various tools and weapons and jewelry, the pottery, the kinds of houses, and even the ways of burying the dead tend to fit into pictures. Some archeologists call all of the things that go together to make such a picture an _assemblage_. The assemblage of the first layer of Schliemann’s Troy was as different from that of the seventh layer as our 1900 mail-order catalogue is from the one of today. The archeologists who came after Schliemann began to notice other things and to compare them with occurrences in modern times. The idea that people will buy better mousetraps goes back into very ancient times. Today, if we make good automobiles or radios, we can sell some of them in Turkey or even in Timbuktu. This means that a few present-day types of American automobiles and radios form part of present-day “assemblages” in both Turkey and Timbuktu. The total present-day “assemblage” of Turkey is quite different from that of Timbuktu or that of America, but they have at least some automobiles and some radios in common.