<p style="font-stretch: normal; line-height: normal; font-family: ".PingFang SC"; color: rgb(69, 69, 69);"><span style="font-family: ".PingFangSC-Regular"; font-size: 17pt;">厦门岛内的普遍海滩上是沙子，而海沧区的海滩上主要是碎石，那到底为什么海滩上会是时碎石而有时是沙子呢？</span></h3><h3>
</h3><p style="font-stretch: normal; line-height: normal; font-family: ".PingFang SC"; color: rgb(69, 69, 69);"><span style="font-family: ".PingFangSC-Regular"; font-size: 17pt;">沙滩上的沙子其实就是非常小颗粒的石头经风化侵蚀，再经海水经年累月地打磨的产物（重石</span><span style="font-family: ".SFUIText"; font-size: 17pt;">-</span><span style="font-family: ".PingFangSC-Regular"; font-size: 17pt;">碎石</span><span style="font-family: ".SFUIText"; font-size: 17pt;">-</span><span style="font-family: ".PingFangSC-Regular"; font-size: 17pt;">沙子）而要形成大规模的海滩，日积月累水滴石穿得以百万年为单位。</span></h3><h3>
</h3><p style="font-stretch: normal; line-height: normal; font-family: ".PingFang SC"; color: rgb(69, 69, 69);"><span style="font-family: ".PingFangSC-Regular"; font-size: 17pt;">如果想在河流的入海处想看到干净松软想让人踩着玩的海滩，首先这条河流得够长。河流长能够让侵蚀后的碎石有足够的时间进行冲刷和打磨，颗粒变得更加细小而光滑。如果流经的时间相对短</span><span style="font-family: ".SFUIText"; font-size: 17pt;">/</span><span style="font-family: ".PingFangSC-Regular"; font-size: 17pt;">距离短，碎石没有被充分地打磨的机会，那么在海滩形成的可能就不是一片沙滩而就是石子。</span></h3><h3>
</h3><p style="font-stretch: normal; line-height: normal; font-family: ".PingFang SC"; color: rgb(69, 69, 69);"><span style="font-family: ".PingFangSC-Regular"; font-size: 17pt;">除了长时间的风化侵蚀的原因，在厦门这种滨海城市，还有源源不断浪花冲击的原因。</span></h3><h3>
</h3><p style="font-stretch: normal; line-height: normal; font-family: ".PingFang SC"; color: rgb(69, 69, 69);"><span style="font-family: ".PingFangSC-Regular"; font-size: 17pt;">而依靠海潮汐能形成沙滩首先需要该海岸是缓坡，缓坡上的沙粒容易堆积，在退潮的时候不容易被海水冲带走，如果是陡坡，则会因摩擦力不足而被海水带走</span><span style="font-family: ".SFUIText"; font-size: 17pt;"> </span><span style="font-family: ".PingFangSC-Regular"; font-size: 17pt;">。</span></h3><h3>
</h3><p style="font-stretch: normal; line-height: normal; font-family: ".PingFang SC"; color: rgb(69, 69, 69);"><span style="font-family: ".PingFangSC-Regular"; font-size: 17pt;">所以在厦门的海边才会出现碎石和沙子都存在的场景</span></h3><h3>
</h3><p style="font-stretch: normal; line-height: normal; font-family: ".SF UI Text"; color: rgb(69, 69, 69); min-height: 20.3px;"><span style="font-family: ".SFUIText"; font-size: 17pt;"></span><br></h3><h3>
</h3>