PLEASEEEEE HELP - EARTH SCIENCE

You are an archaeologist trying to determine the type of volcano that erupted thousands of years ago. All you have are a few lava samples from the volcano's remains. You test your lava samples and determine that the magma they formed from must have had a low viscosity but a high gas content. You also determine that somes of the rock is basalt. Which kind of volcano have you discovered? Describe in detail how that volcano formed.